Broad-band, low frequency, high-amplitude, long time duration, oscillating airway pressure breathing apparatus and method utilizing bubbles

ABSTRACT

It has been discovered that high amplitude, low frequency, broadband spectrum pressure oscillations of sufficient time duration can help stabilize lung volumes and improve gas exchange in a patient receiving ventilation assistance by helping to recruit and stabilize alveoli. A novel device is presented which can produce pressure oscillations having high amplitudes, a low broad-band frequency spectrum and long time duration. Additionally, the device can maintain a patient&#39;s mean airway pressure at one or more controlled levels. The device can control the oscillatory amplitude, frequency range and composition, time duration, and mean airway pressure levels by adjusting certain device parameters, such as the angle and depth of the device in a fluid. A device and mechanical system for remotely adjusting and measuring the angle of the device in a fluid are also disclosed. Furthermore, a device and system are disclosed that can deliver pressure oscillations having high amplitudes, a low broad-band frequency spectrum, long time duration, and multiple mean airway inspiratory and expiratory pressure levels. The device and system also provide means for controlling respiration timing in a patient, including: breaths per minute, inspiratory time, and the ratio of inspiratory to expiratory time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityto International Application PCT/US2009/039957, filed Apr. 8, 2009,which designated the United States and was published in English, andclaims priority to U.S. provisional Application No. 61/044,002, filedApr. 10, 2008 and U.S. Provisional Application No. 61/150,670, filedFeb. 6, 2009, the disclosures of which are hereby expressly incorporatedby reference in their entireties.

FIELD OF THE INVENTION

Embodiments described herein concern compositions and methods thatassist gas exchange and stabilize lung volume in a host. Someembodiments relate to compositions and methods that employ an angledconduit submersed in a liquid, which promotes efficient gas exchange andstabilizes lung volume when low frequency, high-amplitude oscillatingpressure waves are produced.

BACKGROUND OF THE INVENTION

Babies born before 37 completed weeks of pregnancy are called premature.While many of these babies do well, some go on to have lifelong healthproblems. Approximately 60,000 infants with birth weights under 1500 g(about 1.5% of all newborns) are born in the United States each year andabout 20% of these infants develop chronic lung disease (Births: finaldata for 2003. Hyattsville, Md.: National Center for Health Statistics,Centers for Disease Control and Prevention, 2005).

Severely premature infants have underdeveloped lungs and insufficientsurfactant to maintain stable lung volumes. This condition may lead toRespiratory Distress Syndrome (also called hyaline membrane disease) andprogress to chronic lung disease, a major contributor to preterm infantmorbidity and mortality. Chronic Lung disease in the premature isassociated with infants requiring mechanical ventilation viaendotracheal tube.

Continuous positive airway pressure (CPAP) has been a mainstay for thetreatment of preterm infants in respiratory distress for many years.CPAP provides maintenance of the mean airway pressure throughout thebreath cycle to help open and maintain unstable alveoli, which aretypically underdeveloped and surfactant deficient. CPAP is frequentlyapplied to patients using commercially available mechanical ventilators.CPAP can be applied to infants either nasally or via an endotrachealtube. Unfortunately, the vast majority of mechanical ventilators are notdesigned to be used with nasal prongs.

The purchase and maintenance costs of mechanical ventilators render themimpractical for use as CPAP devices. CPAP via endotracheal tube is knownto increase chronic lung disease in preterm infants. Bronchopulmonarydysplasia makes up the majority of infants with chronic lung disease.Mechanical ventilator devices are complex to operate, requiring asubstantial investment to acquire and maintain the devices, as well as,to train the care givers to properly administer the treatment.Importantly, mechanical ventilator devices do not provide broadbandoscillations in airway pressure. The high frequency oscillatoryventilator systems described in U.S. Pat. Nos. 4,805,612 4,481,944 and5,752,506, for example, are capable of delivering large oscillations inairway pressure. However, these devices can only deliver largeoscillations in airway pressure at a single frequency (selected by theoperator).

Conventional Bubble CPAP (B-CPAP) is thought to improve ventilation inpremature infants. By bubbling mechanical ventilator CPAP gases througha fluid with a simple conduit that is submersed vertically in the fluid,B-CPAP causes an infant's chest to vibrate at high frequencies such thatthe infant breathes at a lower respiratory rate than an infant receivingsimple ventilator CPAP. Pillow, et al. (6 (Pediatr Res 57: 826-830,2005)) demonstrated in a mechanical lung model that B-CPAP createsoscillations in airway pressure with predominant frequencies in theranges of about 10 to 20 Hz and 40 to 100 Hz, for example. In anotherstudy, Pillow et al. (7, Am J Respir Crit Care Med Vol 176. pp 63-69,2007) showed that B-CPAP applied to preterm lambs breathingspontaneously had improved oxygen levels and tended to reach stable lungvolumes at lower airway pressures than lambs receiving CPAP generated bya mechanical ventilator. The B-CPAP device used in the studies by Pillowet al., is described in U.S. Pat. No. 6,805,120 entitled “BreathingAssistance Apparatus.” Pillow et al. attributed the improved lungstability to the broadband frequency spectrum of oscillations in airwaypressure produced by CPAP gas bubbles exiting the vertically orientedconduit submersed in water. The device described by Pillow et al.,however, produces small amplitude pressure oscillations that aredelivered at a relatively high range of frequencies to the airway of thehost, resulting in low amplitude and low time duration pressure wavesthat do not deliver sufficient gas to the host's lungs.

Nekvasil, et. al., (1992 {hacek over (C)}s. Pediat., 47, 8:465-470)demonstrated that high frequency oscillations in airway pressure can becreated using a B-CPAP device comprising a glass funnel placedhorizontally under a fluid. Placed in this configuration the deviceprovides higher amplitude oscillations in airway pressure, but at anarrow frequency band with low time duration. Thus, although theamplitude of oscillations is high for one frequency (about 1.1 Hz), thevolume of gas delivered to the patient is still inadequate because thetime duration of the pressure wave is not long enough to push sufficientamounts of gas into the patient's lungs.

Presently, in many neonatal intensive care units, preterm infantsrequiring respiratory assistance are place on nasal B-CPAP. If theinfants fail to meet established gas exchange criteria, they areintubated and placed on mechanical ventilation. A device is needed thatcan maintain gas exchange and alveolar stability in infants failingB-CPAP and that reduces the number of infants requiring intubation andmechanical ventilation. A respiratory assistance device is needed thatcan reduce the work of breathing of patients and stabilize the lungs bymaintaining mean airway pressures throughout the breath cycle. It isalso desirable to provide better gas exchange than that provided bysingle frequency ventilators, B-CPAP, or funnel B-CPAP devices. Forinfants requiring mechanical ventilation, a device is need that can beapplied via either nasal prongs or endotracheal tube at low peak airwaypressures. Additionally, it is desirable to provide a respiratoryassistance device that is simple in design, easy to operate, andinexpensive to manufacture.

SUMMARY OF THE INVENTION

It has been discovered that relatively high amplitude, low frequency,broadband spectrum pressure oscillations of sufficient time duration canhelp stabilize lung volumes and improve gas exchange in a patientreceiving ventilation assistance. Embodiments described herein canproduce pressure oscillations having high amplitudes, a low broad-bandfrequency spectrum and long time duration. Additionally, the embodimentsdescribed herein maintain a patient's mean airway pressure at one ormore controlled levels. In application, a user can control theoscillatory amplitude, frequency range and composition, time duration,and mean airway pressure levels by adjusting certain device parameters,such as the angle and depth of the device in a fluid. Some embodimentsalso include a mechanical system for remotely adjusting and measuringthe angle of the device in a fluid. Additional embodiments includedevices and systems that deliver pressure oscillations having highamplitudes, a low broad-band frequency spectrum, long time duration, andmultiple mean airway inspiratory and expiratory pressure levels. Theseembodiments also have features that allow a user to select and modulaterespiration timing in a patient, including: breaths per minute,inspiratory time, and the ratio of inspiratory to expiratory time.

Low frequency, broad-band, high amplitude and long duration oscillationsin airway pressure are beneficial for patients that have difficultyremoving pulmonary secretions. The embodiments described herein can beused to ventilate patients of all ages, including adults. Examples ofpatients that will benefit from the technology described herein include,but are not limited to: patients with bronchiolitis, pneumonia, cysticfibrosis, neonates with meconium aspiration syndrome, congenitaldiaphragmatic hernia, and congenital heart disease, premature infantswith lung disease or larger infants or adults that require respiratoryassistance during surgery and post operative care. Additionally, severalembodiments described herein are useful in remote clinical settings, inclinical facilities that do not have access to mechanical ventilators,or in clinical settings that lack power such as catastrophic disastersites.

In one embodiment, a pressure regulating breathing assistance apparatushaving a pressurized gas source, a fluid-filled container and a conduitis provided. The conduit includes proximal and distal ends. The proximalend is adapted for connection to the pressurized gas source and to apatient interface intermediate the proximal and distal ends of theconduit. The distal end of the conduit has at least one peak inspiratorypressure control conduit that is configured to be submerged in thefluid-filled container at varying depths. The distal end of the conduitalso has at least one positive end-expiratory pressure control conduitthat is also configured to be submerged in the body of fluid at varyingdepths. The distal end of the conduit also has a valve intermediate theat least one peak inspiratory pressure control conduit and the at leastone positive end-expiratory pressure control conduit.

In some embodiments, the distal end of the at least one peak inspiratorypressure control conduit and/or the at least one positive end-expiratorypressure control conduit has any angle except 0 and 90 degrees withrespect to a vertical axis so long as the device is configured toproduce a high amplitude, low frequency broadband oscillating pressurewave having more than 50% of its average power spectra occur below about7 Hz when the bias gas flow is at least 2 L/min in a model test lungsystem comprising a hermetically sealed silastic lung within acalibrated plethysmograph. In other embodiments, the distal end of thepositive end-expriratory pressure control conduit is angled greater than90 degrees with respect to a vertical axis. In further embodiments, thedistal end of the peak inspiratory pressure control conduit and/or theend-expriratory pressure control conduit is angled greater than or equalto between about 91-170 degrees, between about 95-165 degrees, betweenabout 100-160 degrees, between about 105-155 degrees, between about110-150 degrees, between about 115-145 degrees, between about 120-140degrees, between about 125-135 degrees, between about 130-140 degrees,or about 135 degrees with respect to a vertical axis. In one particularembodiment, the distal end of the peak inspiratory pressure controlconduit and/or the end-expriratory pressure control conduit is angled toabout 135 degrees with respect to a vertical axis.

In certain embodiments, the distal end of the peak inspiratory pressurecontrol conduit and/or the end-expriratory pressure control conduit issubstantially circular having an inside diameter of between about 1-3cm, between about 1.2-2.0 cm, between about 1.3-1.8 cm, between about1.4-1.6 cm, or about 1.5 cm.

In further embodiments, the angled portion of the distal end of the peakinspiratory pressure control conduit and/or the end-expriratory pressurecontrol conduit has a length of between about 5-12 cm, between about6-11 cm, between about 7-10 cm, between about 8-9.5 cm, or about 9 cm.

In other embodiments, the distal end of the peak inspiratory pressurecontrol conduit and/or the end-expriratory pressure control conduit issubmerged to a depth of about between 3-200 cm, between about 5-11 cm,about 5 cm, about 7 cm, about 9 cm, or about 11 cm.

In yet other embodiments, the fluid has a density of between about0.8-1.1 g/cm3 at 20° C., between about 0.85-1.05, between about 0.9-1.0g/cm3 at 20° C., or about 1.0 g/cm3 at 20° C. In one particularlypreferred embodiment, the fluid is water.

In preferred embodiments, the peak inspiratory pressure control conduitis configured to produce an oscillating pressure wave having more than50% of its average power spectra occur below about 7 Hz when the biasflow of gas is at least 2 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph. Inother preferred embodiments, the peak inspiratory pressure controlconduit is configured to produce airway pressure oscillation frequenciesof between about 1-10 Hz, between about 2-9 Hz, between about 2-7 Hz, orbetween about 2-5 Hz when the bias flow is 6 L/min in a model test lungsystem comprising a hermetically sealed silastic lung within acalibrated plethysmograph. In a particularly preferred embodiment, thepeak inspiratory pressure control conduit is configured to deliver anaverage volume of gas greater than about 3.0 ml when the bias flow ofgas is 8 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.

In some embodiments, a conduit swivel member is used at the distal endof the conduit to adjust the angle of the distal end of the conduit withrespect to a vertical axis. The conduit swivel member can also have aplurality of marks that indicate the angle of the distal end of theconduit with respect to the vertical axis. The conduit swivel member canbe automated such that a user can manually or automatically adjust theangle of said distal end of said conduit with respect to the verticalaxis. Additionally, a computer can also be used to operate the swivelmember upon user instruction or programmed executable instructions tothereby automatically adjust the angle of the distal end of the conduitwith respect to the vertical axis.

In one embodiment, a breathing assistance apparatus is provided having apressurized gas source, a container holding a liquid, and a conduit. Theconduit has proximal and distal ends, the proximal end being adapted forconnection to the pressurized gas source, and the distal end of theconduit being configured to be submerged in the liquid. The conduit isalso adapted for connection to a patient interface intermediate theproximal and distal ends of the conduit and the distal end of theconduit is angled greater than 90 degrees with respect to a verticalaxis. In other embodiments, the distal end of the conduit is angledgreater than or equal to between about 91-170 degrees, between about95-165 degrees, between about 100-160 degrees, between about 105-155degrees, between about 110-150 degrees, between about 115-145 degrees,between about 120-140 degrees, between about 125-135 degrees, betweenabout 130-140 degrees, or about 135 degrees with respect to a verticalaxis. In one particularly preferred embodiment, the distal end of theconduit is angled to about 135 degrees with respect to a vertical axis.

In certain embodiments, the distal end of the conduit is substantiallycircular having an inside diameter of between about 1-3 cm, betweenabout 1.2-2.0 cm, between about 1.3-1.8 cm, between about 1.4-1.6 cm, orabout 1.5 cm.

In further embodiments, the angled portion of the distal end of theconduit has a length of between about 5-12 cm, between about 6-11 cm,between about 7-10 cm, between about 8-9.5 cm, or about 9 cm.

In some embodiments, the distal end of the conduit is submerged to adepth of about between 3-200 cm, between about 5-11 cm, about 5 cm,about 7 cm, about 9 cm, or about 11 cm.

In certain embodiments, the fluid has a density of between about 0.8-1.1g/cm3 at 20° C., between about 0.85-1.05, between about 0.9-1.0 g/cm3 at20° C., or about 1.0 g/cm3 at 20° C. In a particularly preferredembodiment, the fluid is water.

In preferred embodiments, the conduit is configured to produce anoscillating pressure wave having more than 50% of its average powerspectra occur below about 7 Hz when the bias flow of gas is 2 L/min in amodel test lung system comprising a hermetically sealed silastic lungwithin a calibrated plethysmograph. In other preferred embodiments, theconduit is configured to produce an oscillating pressure wave havingmore than 50% of its average power spectra occur between about 2-5 Hzwhen the bias flow of gas is 2 L/min and 1-9 Hz when the bias flow ofgas is 12 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph. In oneparticularly preferred embodiment, the conduit is configured to produceairway pressure oscillation frequencies of between about 1-10 Hz,between about 2-9 Hz, between about 2-7 Hz, or between about 2-5 Hz whenthe bias flow is 6 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph. Inanother particularly preferred embodiment, the conduit is configured todeliver an average volume of gas of about 4.0 ml when the bias flow ofgas is 8 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.

In some embodiments, the breathing assistance apparatus has a conduitswivel member at the distal end of the conduit that is configured toadjust the angle of the distal end of the conduit with respect to avertical axis. The conduit swivel member can also have a plurality ofmarks that indicate the angle of the distal end of said conduit withrespect to the vertical axis. Additionally, the conduit swivel membercan also be automated such that a user or a computer can automaticallyadjust the angle of the distal end of the conduit with respect to thevertical axis. And in certain embodiments, the gas source is a gascompressor or a mechanical or electromechanical ventilator.

In one embodiment, a bubble continuous positive airway pressure (B-CPAP)device is provided having a pressurized gas source, a container holdinga liquid and a conduit. The conduit has proximate and distal ends. Theproximal end is adapted for connection to the pressurized gas source.The conduit is also adapted for connection to a patient interfaceintermediate the proximal and distal ends. The distal end of the conduitis configured to be submerged in the liquid at varying depths and thedistal end of the conduit has a conduit swivel member that is configuredto adjust the angle of the distal end of the conduit with respect to avertical axis. The conduit swivel member can have a plurality of marksthat indicate the angle of the distal end of the conduit with respect tothe vertical axis. Furthermore, the conduit swivel member can beautomated such that a user, a computer, a processor or a machine canautomatically adjust the angle of the distal end of the conduit withrespect to the vertical axis. For example, a computer can be configuredto operate the conduit swivel member upon user instruction toautomatically adjust the angle of the distal end of the conduit withrespect to a vertical axis. In some embodiments, the pressurized gassource comprises a gas compressor or a mechanical or electromechanicalventilator.

In another embodiment, a bubble continuous positive airway pressure(B-CPAP) device is provided having a pressurized gas source, a containerholding a liquid and a conduit. The conduit has proximate and distalends. The proximal end is adapted for connection to the pressurized gassource. The conduit is also adapted for connection to a patientinterface intermediate the proximal and distal ends. The distal end ofthe conduit is submerged in the liquid and configured to produce anoscillating pressure wave having more than 50% of its average powerspectra occur between about 2-5 Hz when the bias flow of gas is 2 L/minand 1-9 Hz when the bias flow of gas is 12 L/min in a model test lungsystem comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

In further embodiments, a bubble continuous positive airway pressure(B-CPAP) device is provided having a pressurized gas source, a containerholding a liquid and a conduit. The conduit has proximate and distalends. The proximal end is adapted for connection to the pressurized gassource. The conduit is also adapted for connection to a patientinterface intermediate the proximal and distal ends. The distal end ofthe conduit is submerged in the liquid and configured to deliver anaverage volume of gas of about 4.0 ml when the bias flow of gas is 8L/min in a model test lung system comprising a hermetically sealedsilastic lung within a calibrated plethysmograph.

In one embodiment, a method is disclosed for increasing the volume ofgas delivered to a subject by a bubble continuous positive airwaypressure (B-CPAP) device by providing a any of the breathing assistanceapparatuses disclosed herein; adjusting the angle of the distal end ofthe conduit of the breathing assistance apparatus to greater than 90degrees with respect to a vertical axis; releasing gas from thepressurized gas source into the breathing assistance apparatus, orB-CPAP device; and delivering the gas to the subject. In someembodiments, the distal end of the conduit is adjusted to an anglegreater than or equal to between about 91-170 degrees, between about95-165 degrees, between about 100-160 degrees, between about 105-155degrees, between about 110-150 degrees, between about 115-145 degrees,between about 120-140 degrees, between about 125-135 degrees, betweenabout 130-140 degrees, or about 135 degrees with respect to a verticalaxis. In a particularly preferred embodiment, the distal end of theconduit is adjusted to an angle of about 135 degrees with respect to avertical axis. In still other embodiments, the distal end of the conduitis adjusted to any angle, except 0 and 90 degrees, so long as thebreathing assistance apparatus is configured to produce an oscillatingpressure wave having more than 50% of its average power spectra occurbelow about 7 Hz when the bias flow of gas is at least 2 L/min in amodel test lung system comprising a hermetically sealed silastic lungwithin a calibrated plethysmograph.

In another embodiment, a breathing assistance apparatus is providedhaving a pressurized gas source, a container holding a liquid, and aconduit. The conduit has proximal and distal ends, the proximal endbeing adapted for connection to the pressurized gas source, and thedistal end of the conduit being configured to be submerged in theliquid. The conduit is also adapted for connection to a patientinterface intermediate the proximal and distal ends of the conduit. Thedistal end of the conduit can have any angle with respect to a verticalaxis, except 0 and 90 degrees, so long as the conduit is configured toproduce an oscillating pressure wave having more than 50% of its averagepower spectra occur below about 7 Hz when the bias flow of gas is atleast 2 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.

In another embodiment, a breathing assistance apparatus is providedhaving a pressurized gas source, a container holding a liquid, and aconduit. The conduit has proximal and distal ends, the proximal endbeing adapted for connection to the pressurized gas source, and thedistal end of the conduit being configured to be submerged in theliquid. The conduit is also adapted for connection to a patientinterface intermediate the proximal and distal ends of the conduit. Thedistal end of the conduit can have any angle with respect to a verticalaxis, except 0 and 90 degrees, so long as the conduit is configured toproduce an oscillating pressure wave having more than 50% of its averagepower spectra occur between about 2-5 Hz when the bias flow of gas is 2L/min and 1-9 Hz when the bias flow of gas is 12 L/min in a model testlung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

In yet another embodiment, a breathing assistance apparatus is providedhaving a pressurized gas source, a container holding a liquid, and aconduit. The conduit has proximal and distal ends, the proximal endbeing adapted for connection to the pressurized gas source, and thedistal end of the conduit being configured to be submerged in theliquid. The conduit is also adapted for connection to a patientinterface intermediate the proximal and distal ends of the conduit. Thedistal end of the conduit can have any angle with respect to a verticalaxis, except 0 and 90 degrees, so long as the conduit is configured toproduce airway pressure oscillation frequencies of between about 1-10Hz, between about 2-9 Hz, between about 2-7 Hz, or between about 2-5 Hzwhen the bias flow is 6 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph.

In further embodiments, a breathing assistance apparatus is providedhaving a pressurized gas source, a container holding a liquid, and aconduit. The conduit has proximal and distal ends, the proximal endbeing adapted for connection to the pressurized gas source, and thedistal end of the conduit being configured to be submerged in theliquid. The conduit is also adapted for connection to a patientinterface intermediate the proximal and distal ends of the conduit. Thedistal end of the conduit can have any angle with respect to a verticalaxis, except 0 and 90 degrees, so long as the conduit is configured todeliver an average volume of gas of about 4.0 ml when the bias flow ofgas is 8 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a patient ventilation system utilizing a conduitsubmerged in fluid and configured to modulate airway pressures.

FIGS. 2A-B shows a silastic test lung model housed within aplethysmograph and a method for selecting oscillations in airwaypressure for measurement.

FIG. 3 demonstrates methods used to determine frequency band from a fastFourier transformation of the original pressure signal.

FIG. 4 shows how the frequency band was determined from another signalat different conditions from FIG. 3.

FIG. 5 depicts the delivered volume of gas to a test lung with differentbubbler angles.

FIG. 6 illustrates how the amplitudes of oscillations in airway pressurevary with bubbler angle.

FIG. 7 depicts how the amplitudes of oscillations in lung volume varywith bubbler angle.

FIG. 8 shows how the amplitudes of oscillations in airway pressure andlung volume vary with bubbler angle in a different embodiment.

FIG. 9 demonstrates how the amplitudes of oscillations in airwaypressure vary with different bias flow rates for different bubblerangles.

FIG. 10 illustrates how the amplitudes of oscillations in lung volumevary with different bias flow rates for different bubbler angles.

FIG. 11 shows how the depth of the bubbler in a fluid affects theamplitude of oscillations in airway pressure.

FIG. 12 shows how the bubbler diameter and length affect the amplitudeof oscillations in airway pressure.

FIG. 13 illustrates how the power spectra vary with frequency and angle.

FIG. 14 demonstrates how the power spectra vary with bias flow rate.

FIG. 15 shows how the normalized amplitude of the power spectra varieswith different bias flow rates for a funnel shaped bubbler.

FIG. 16 shows the delivered lung volumes corresponding to different biasflow rates for a funnel shaped bubbler.

FIG. 17 shows the funnel data of FIG. 15 (gray) superimposed withoscillating airway pressure waves obtained from a bubbler set to 135°(black).

FIG. 18 shows how the normalized amplitude of the power spectra varieswith different bias flow rates for a bubbler set to 135°.

FIG. 19 illustrates the delivered lung volume for a given bias flow ratefor a bubbler set to 135°.

FIG. 20 shows the number of adequately oxygenated paralyzed animals withbubbler angles of 0°, 90° and 135°.

FIG. 21 demonstrates the oxygenation and ventilation characteristics oftwo different ventilation systems.

FIG. 22 depicts the work of breathing and the oxygenation andventilation characteristics of two different ventilation systems.

FIG. 23 illustrates a top perspective view of a gas-flow control conduitconfigured to vary the exit angle of gas from the conduit.

FIG. 24 depicts a side view of the gas-flow control conduit of FIG. 23submerged in a fluid-filled container.

FIG. 25 shows a top perspective view of the gas-flow control tube ofFIG. 24 adjusted to direct gas flow in a downward direction.

FIG. 26 illustrates a top perspective view of the gas-flow controlconduit of FIG. 23 with a mechanical gear system configured to vary theexit angle of gas from the conduit.

FIG. 27 depicts a closer view of the gas-flow control conduit with themechanical gear system of FIG. 26.

FIG. 28 shows the patient ventilation system of FIG. 1 with a gas-flowcontrol conduit configured to vary the exit angle of gas from theconduit.

FIG. 29 shows a patient ventilation system utilizing multiple bubblerssubmerged in fluid and configured to differentially modulate inspiratoryand expiratory airway pressures.

FIG. 30 compares the airway pressure signals generated by a conventionalventilator and a Hansen Ventilator and demonstrates the two differentgas flow directions during inhalation (valve closed) and exhalation(valve open).

FIG. 31 compares the oxygenation and ventilation characteristics betweena conventional ventilator and a Hansen Ventilator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments described herein provide pressure oscillations having highamplitudes, a low-broadband frequency spectrum, and sufficient timeduration to a patient's airway to help stabilize lung volumes andimprove gas exchange. Some embodiments, for example, maintain apatient's mean airway pressure at one or more controlled levels duringspontaneous breathing and apnea. Some embodiments allow a user tocontrol the oscillatory amplitude, frequency range and composition, timeduration, and mean airway pressure levels by adjusting certain deviceparameters, such as the bias flow, angle and depth of the device in afluid. In certain embodiments, the device comprises a mechanical systemfor remotely adjusting and measuring the angle of the device in a fluid.In other embodiments, the device and system can deliver pressureoscillations having high amplitudes, a low broad-band frequencyspectrum, long time duration, and multiple mean airway inspiratory andexpiratory pressure levels. Some embodiments can also provide means forcontrolling respiration timing in a patient, including: breaths perminute, time to inspiration and the ratio of inspiratory to expiratorytime.

FIG. 1 illustrates a patient ventilation system 100 utilizing a bubbler170 (also referred to herein as an “angled portion” of the submergedconduit, a “bubbleator,” or a “High Amplitude Bubbler” (HAB)) submergedin a fluid 165 and configured to modulate the frequency and amplitudesof airway pressures in a patient (not shown) attached to the device atthe patient interface 130. A gas source 110 supplies a bias flow ofpressurized gas through gas source conduit 141, which splits at 142 intopatient conduit 150 and bubbler conduit 140. The lengths andcross-sectional shapes of the bubbler 170, the gas source conduit 141,the patient conduit 150 and the bubbler conduit 140 are preferably shortand substantially circular or slightly oval in shape. However, any orall of the bubbler 170, the gas source conduit 141, the patient conduit150 and the bubbler conduit 140 can have any length or cross-sectionalshape including but not limited to: square, rectangular, triangularetc., without departing from the spirit of present disclosure.

The length of the bubbler 170 is preferably measured from any distaledge of the bubbler exit portion 180 to any portion of the bubbler elbow175, or any point inside of the bubbler elbow 175. However, the lengthof the bubbler 170 can also be measured from any surface of the bubblerexit portion 180 to any portion of the of the bubbler conduit 140including any outside surface or edge, any inside surface or edge orfrom any point inside of the bubbler conduit 140. In some embodiments,the length of the bubbler 170 as measured from the distal edge of thebubbler exit portion 180 to the outside of the bubbler elbow 175 or anypoint inside of the bubbler elbow 175 is about 0.5 cm to 100 cm,desirably 1 cm to 50 cm, preferably about 3 cm to 15 cm as measured fromthe distal edge of the bubbler exit portion 180 to the outside of thebubbler elbow 175 or any point inside of the bubbler elbow 175. That is,in some embodiments, the length of the bubbler 170 as measured from thedistal edge of the bubbler exit portion 180 to the outside of thebubbler elbow 175 or any point inside of the bubbler elbow 175 can be atleast, equal to, greater than or any number in between about 1 cm, 2 cm,3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm, 14cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 21 cm, 22 cm, 23 cm, 24cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30 cm, 31 cm, 32 cm, 33 cm, 34cm, 35 cm, 36 cm, 37 cm, 38 cm, 39 cm, 40 cm, 41 cm, 42 cm, 43 cm, 44cm, 45 cm, 46 cm, 47 cm, 48 cm, 49 cm and 50 cm. Although not adesirable embodiment, the length of the bubbler 170 as measured from thedistal edge of the bubbler exit portion 180 to the outside of thebubbler elbow 175 or any point inside of the bubbler elbow 175 can be atleast, equal to, greater than or any number in between about 50 cm, 55cm, 60 cm, 65 cm, 70 cm, 75 cm, 80 cm, 85 cm, 90 cm, 95 cm, and 100 cm.In some embodiments, the length of the bubbler 170 as measured from thedistal edge of the bubbler exit portion 180 to the outside of thebubbler elbow 175 or any point inside of the bubbler elbow 175 can beany length so long as the device is configured to produce a highamplitude, low frequency broadband oscillating pressure wave having morethan 50% of its average power spectra occur below about 10 Hz, 9 Hz, 8Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the bias gas flow is atleast 2 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.

In certain embodiments of the bubbler 170, the diameter of the bubbler170 is about 0.1 cm to 10 cm, desirably 0.25 cm to 5 cm, preferably 1 cmto 2 cm. That is, in some embodiments, the diameter of the bubbler 170can be at least, equal to, greater than or any number in between about0.25 cm, 0.5 cm, 0.75 cm, 1.0 cm, 1.25 cm, 1.5 cm, 1.75 cm, 2.0 cm, 2.25cm, 2.5 cm, 2.75 cm, 3.0 cm, 3.25 cm, 3.5 cm, 3.75 cm, 4.0 cm, 4.25 cm,4.5 cm, 4.75 cm and 5.0 cm. Although not a desirable embodiment, thediameter of the bubbler 170 can be at least, equal to, greater than orany number in between about 5 cm, 5.5 cm, 6.0 cm, 6.5 cm, 7.0 cm, 7.5cm, 8.0 cm, 8.5 cm, 9.0 cm, 9.5 cm, and 10.0 cm. In some embodiments,the diameter of the bubbler 170 can be any size so long as the device isconfigured to produce a high amplitude, low frequency broadbandoscillating pressure wave having more than 50% of its average powerspectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a model testlung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

In some embodiments, the cross-sectional area of the bubbler 170, asdefined by a plane transverse to the longitudinal axis of the bubbler170, is about 0.005 cm² to 350 cm², desirably 0.2 cm² to 80 cm², andpreferably about 3.10 cm² to 13 cm². That is, in some embodiments, thecross-sectional area of the bubbler 170 can be at least, equal to,greater than, or any number in between about 0.2 cm², 0.5 cm², 0.75 cm²,1 cm², 2 cm², 3 cm², 4 cm², 5 cm², 6 cm², 7 cm², 8 cm², 9 cm², 10 cm²,11 cm², 12 cm², 13 cm², 14 cm², 15 cm², 16 cm², 17 cm², 18 cm², 19 cm²,20 cm², 25 cm², 30 cm², 35 cm², 40 cm², 45 cm², 50 cm², 55 cm², 60 cm²,65 cm², 70 cm², 75 cm², and 80 cm². Although not a desirable embodiment,the cross-sectional area of the bubbler 170 can be at least, equal to,greater than, or any number in between about 80 cm², 90 cm², 100 cm²,110 cm², 120 cm², 130 cm², 140 cm², 150 cm², 160 cm², 170 cm², 180 cm²,190 cm², 200 cm², 210 cm², 220 cm², 230 cm², 240 cm², 250 cm², 260 cm²,270 cm², 280 cm², 290 cm², 300 cm², 310 cm², 320 cm², 330 cm², 340 cm²,and 350 cm². In some embodiments, the cross-sectional area of thebubbler 170 can be any size so long as the device is configured toproduce a high amplitude, low frequency broadband oscillating pressurewave having more than 50% of its average power spectra occur below about10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the biasgas flow is at least 2 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph.

The depth at which the bubbler 170 is submerged in the fluid 165 can bemeasured from the fluid surface to the bubbler elbow 175, the bubblerexit portion 180, or any other portion of the bubbler 170 there between.In some embodiments of the patient ventilation system 100, the depth atwhich the bubbler 170 is submerged in the fluid 165, as measured fromthe fluid surface to either the bubbler elbow 175, the bubbler exitportion 180, or any other portion of the bubbler 170 there between, isabout 0.1 cm to 500 cm, desirably 1 cm to 200 cm, and preferably about1.5 cm to 30 cm. That is, in some embodiments, the depth of the bubbler170 as measured from the fluid surface to either the bubbler elbow 175,the bubbler exit portion 180, or any other portion of the bubbler 170there between can be at least, equal to, greater than, or any number inbetween about 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30cm, 31 cm, 32 cm, 33 cm, 34 cm, 35 cm, 36 cm, 37 cm, 38 cm, 39 cm, 40cm, 41 cm, 42 cm, 43 cm, 44 cm, 45 cm, 46 cm, 47 cm, 48 cm, 49 cm, 50cm, 51 cm, 52 cm, 53 cm, 54 cm, 55 cm, 56 cm, 57 cm, 58 cm, 59 cm, 60cm, 61 cm, 62 cm, 63 cm, 64 cm, 65 cm, 66 cm, 67 cm, 68 cm, 69 cm, 70cm, 71 cm, 72 cm, 73 cm, 74 cm, 75 cm, 76 cm, 77 cm, 78 cm, 79 cm, 80cm, 81 cm, 82 cm, 83 cm, 84 cm, 85 cm, 86 cm, 87 cm, 88 cm, 89 cm, 90cm, 91 cm, 92 cm, 93 cm, 94 cm, 95 cm, 96 cm, 97 cm, 98 cm, 99 cm, 100cm, 101 cm, 102 cm, 103 cm, 104 cm, 105 cm, 106 cm, 107 cm, 108 cm, 109cm, 110 cm, 111 cm, 112 cm, 113 cm, 114 cm, 115 cm, 116 cm, 117 cm, 118cm, 119 cm, 120 cm, 121 cm, 122 cm, 123 cm, 124 cm, 125 cm, 126 cm, 127cm, 128 cm, 129 cm, 130 cm, 131 cm, 132 cm, 133 cm, 134 cm, 135 cm, 136cm, 137 cm, 138 cm, 139 cm, 140 cm, 141 cm, 142 cm, 143 cm, 144 cm, 145cm, 146 cm, 147 cm, 148 cm, 149 cm, 150 cm, 151 cm, 152 cm, 153 cm, 154cm, 155 cm, 156 cm, 157 cm, 158 cm, 159 cm, 160 cm, 161 cm, 162 cm, 163cm, 164 cm, 165 cm, 166 cm, 167 cm, 168 cm, 169 cm, 170 cm, 171 cm, 172cm, 173 cm, 174 cm, 175 cm, 176 cm, 177 cm, 178 cm, 179 cm, 180 cm, 181cm, 182 cm, 183 cm, 184 cm, 185 cm, 186 cm, 187 cm, 188 cm, 189 cm, 190cm, 191 cm, 192 cm, 193 cm, 194 cm, 195 cm, 196, 197 cm, 198 cm, 199 cm,and 200 cm. Although not a desirable embodiment, the depth of thebubbler 170 as measured from the fluid surface to either the bubblerelbow 175, the bubbler exit portion 180, or any other portion of thebubbler 170 there between can be at least, equal to, greater than, orany number in between about 200 cm, 210 cm, 220 cm, 230 cm, 240 cm, 250cm, 260 cm, 270 cm, 280 cm, 290 cm, 300 cm, 310 cm, 320 cm, 330 cm, 340cm, 350 cm, 360 cm, 370 cm, 380 cm, 390 cm, 400 cm, 410 cm, 420 cm, 430cm, 440 cm, 450 cm, 460 cm, 470 cm, 480 cm, 490 cm, and 500 cm. In someembodiments, the depth at which the bubbler 170 is submerged in thefluid 165, as measured from the fluid surface to either the bubblerelbow 175, the bubbler exit portion 180, or any other portion of thebubbler 170 there between, can be any depth so long as the device isconfigured to produce a high amplitude, low frequency broadbandoscillating pressure wave having more than 50% of its average powerspectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a model testlung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

Continuing with FIG. 1, the frequencies and amplitudes of pressureoscillations can be controlled by adjusting the angle of the bubbler 170placed in the liquid 165. For the purposes of this application, theangle of bubbler 170 can be adjusted between 0° and 180° with respect toa line normal to the surface of the fluid 166, where 0° corresponds tothe bubbler exit portion 180 being oriented straight down, away from thefluid surface 166 and 180° corresponds to the bubbler exit portion 180being oriented straight up, toward the fluid surface 166. Alternatively,or in addition thereto, the angle of bubbler 170 can be adjusted between0° and 180° with respect to a vertical axis defined by gravity andpointing toward the Earth's center of mass, where 0° corresponds to thebubbler exit portion 180 being oriented straight down, toward theEarth's center of mass and 180° corresponds to the bubbler exit portion180 being oriented straight up, away from the Earth's center of mass.

In some embodiments, the angle of the bubbler 170 is about 1° to 89° orabout 91° to 180°, preferably 100° to 170°. That is, in someembodiments, the angle of the bubbler 170 as measured with respect to aline normal to the surface of the fluid 166 or with respect to avertical axis can be at least, equal to, greater than or any number inbetween about 1°, 2°, 3°, 4°, 5°, 6°, 7° 8°, 9°, 10°, 11°, 12°, 13°,14°, 15°, 16°, 17°, 18°, 19°, 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°,28°, 29°, 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°,42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, 51°, 52°, 53°, 54°, 55°,56°, 57°, 58°, 59°, 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°,70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°,84°, 85°, 86°, 87°, 88°, 89°, 91°, 92°, 93°, 94°, 95°, 96°, 97°, 98°,99°, 100°, 101°, 102°, 103°, 104°, 105°, 106°, 107°, 108°, 109°, 110°,111°, 112°, 113°, 114°, 115°, 116°, 117°, 118°, 119°, 120°, 121°, 122°,123°, 124°, 125°, 126°, 127°, 128°, 129°, 130°, 131°, 132°, 133°, 134°,135°, 136°, 137°, 138°, 139°, 140°, 141°, 142°, 143°, 144°, 145°, 146°,147°, 148°, 149°, 150°, 151°, 152°, 153°, 154°, 155°, 156°, 157°, 158°,159°, 160°, 161°, 162°, 163°, 164°, 165°, 166°, 167°, 168°, 169°, 170°,171°, 172°, 173°, 174°, 175°, 176°, 177°, 178°, 179°, and 180°. In someembodiments, the angle of the bubbler 170 as measured with respect to aline normal to the surface of the fluid 166 or with respect to avertical axis can be any angle that is not 0° or 90° so long as thedevice is configured to produce a high amplitude, low frequencybroadband oscillating pressure wave having more than 50% of its averagepower spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a modeltest lung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

FIGS. 23-25 illustrate one embodiment of a swivel device 300 forcontrolling the angle of bubble gases released into a fluid. Referringto FIG. 23, the bubbler conduit 310 is attached to the elbow 320 viaconnector 315. The elbow 320 is a hollow conduit configured to receivebubbler swivel 340 at the distal end of the elbow 330 so as to allow thebubbler swivel 340 to rotate within the elbow 320 and allow the bubblerswivel exit portion 350 to assume different angles. The connectinginterface between the elbow 320 and the bubbler swivel 340 preferablyforms a substantially water tight seal. However, in other embodimentsthe connecting interface formed between the elbow 320 and the bubblerswivel 340 does not form a substantially water tight seal. In oneembodiment, the bubbler swivel 340 and/or elbow 320 have angle markings(not shown) so that the user can visually set and measure the anglemanually. In some embodiments, the bubbler swivel 340 may be automatedsuch that a user or a computer can change or direct the change of thebubbler angle. FIG. 25 shows the bubbler swivel of FIG. 23 adjusteddownward and FIG. 24 shows the bubbler swivel of FIG. 23 immersed in acontainer holding a fluid 400. FIG. 28 shows the device of FIGS. 23-25implemented with the patient ventilation system 100 of FIG. 1.

FIGS. 26 and 27 show another embodiment of the swivel device of FIGS.23-25 employing a mechanical gear and rod mechanism to adjust the angleof the bubbler swivel 680. The operator rotates handle 610 connected toshaft 620, which is secured to elbow 660 at 640, causing gears 671-674to rotate, thereby rotating bubbler swivel 680. This allows the operatorto adjust the bubbler swivel angle from above the fluid. FIG. 27 is acloser view of the device of FIG. 26.

Referring back to FIG. 1, gas delivered by the gas source 110 maycomprise atmospheric gases or any combination, mixture or blend ofsuitable gases, including but not limited to: atmospheric air, oxygen,nitrogen, carbon dioxide, helium, or combinations thereof. The gassource 110 may comprise a gas compressor, a mechanical ventilator, anelectromechanical ventilator, a container of pressurized gas, asubstantially portable container of pre-pressurized gas, a gas-linehookup (such as found in a hospital) or any other suitable source ofpressurized gas, or combinations thereof. The gas source 110 ispreferably controlled or configured to have a substantially constantbias gas flow rate, which can be controlled by the care giver andadjusted according to the individual characteristics of each patient.For example, the patient ventilation system 100 or gas source 110 mayalso include one or more flow control devices (not shown) such as amechanical valve, an electronically controlled mechanical valve, arotameter, a pressure regulator, a flow transducer, or combinationsthereof Bias gas flow rates, which are commonly used in the art,typically range from about 2 L/min to about 10 L/min. However, one ofskill in the art will understand that bias gas flow rates below about 2L/min and above about 10 L/min may also be used. For example, largerpatients generally require larger bias flow rates.

In some embodiments, the bias gas flow rate is about 0.1 L/min to 30L/min, 1 L/min to 20 L/min, preferably 2 L/min to 10 L/min. That is, insome embodiments, the bias gas flow rate can be at least, equal to,greater than or any number in between about 1 L/min, 2 L/min, 3 L/min, 4L/min, 5 L/min, 6 L/min, 7 L/min, 8 L/min, 9 L/min, 10 L/min, 11 L/min,12 L/min, 13 L/min, 14 L/min, 15 L/min, 16 L/min, 17 L/min, 18 L/min, 19L/min, and 20 L/min. Although not a desirable embodiment, the bias gasflow rate can be at least, equal to, greater than or any number inbetween about 20 L/min, 21 L/min, 22 L/min, 23 L/min, 24 L/min, 25L/min, 26 L/min, 27 L/min, 28 L/min, 29 L/min, and 30 L/min. In someembodiments, the bias gas flow rate can be any rate so long as thedevice is configured to produce a high amplitude, low frequencybroadband oscillating pressure wave having more than 50% of its averagepower spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a modeltest lung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

The patient conduit 150 can include a high pressure “pop-off' or“pop-open” safety valve 120 to protect the patient from receiving airwaypressures greater than a pre-determined threshold to help prevent lungdamage and to prevent high pressures from reaching the patient in theunlikely event that the patient circuit is occluded between the patientand the gas exiting the system through the fluid container.Additionally, the patient conduit 150 can include a low pressure“pop-open” or one way valve 125 to protect the patient from receivingairway pressures lower than a pre-determined threshold, for examplesub-atmospheric pressures. In this manner, the one way valve 125 canhelp prevent alveoli from collapsing and/or help prevent the patientfrom inhaling fluid 165. Fresh gas of controlled concentration (notshown) can also be supplied to the one way valve 125.

A Heat and Moisture Exchanger (HME) (not shown) can also be included inthe patient ventilation system 100 to control the temperature andmoisture content of gas delivered to the patient interface.Additionally, the patient ventilation sys4tem 100 can also include avalve system 125 to prevent the patient from re-breathing exhalationgases. For example, if the patient inhalation flow rate is greater thanthe bias flow rate then the patient will tend to rebreathe exhaledgases. A One-way valve 125 can be provided to allow room air, or gas ofa controlled concentration, to help reduce or prevent the patient fromrebreathing exhalation gases.

Bias gas flows from the gas source 110 to the patient interface 130 forinhalation by the patient. The patient interface 130 can be invasive ornon-invasive, including but not limited to: facial or nasal masks, nasalprongs, tube(s) placed in the nasal pharynx, endotracheal tubes,tracheostomy tubes, or combinations thereof Bias gas and patientexhalation gases flow through bubbler conduit 140 to bubbler 170, whichis placed in a container 160 holding a fluid 165. Preferably, the fluid165 comprises water. However, the fluid 165 may comprise any number ofsuitable fluids or liquids exhibiting a wide range of densities, massesand viscosities including, but not limited to: water, oil, ethyleneglycol, ethanol, any fluid containing hydrocarbons, or combinationsthereof.

In some embodiments, the fluid or liquid density is about 0.5 to 1.5g/cm³ at 20° C., desirably about 0.8 to 1.1 g/cm³ at 20° C., andpreferably about 0.85 to 1.05 g/cm³ at 20° C. That is, in someembodiments, the fluid density can be at least, equal to, greater than,or any number in between about 0.50 g/cm³ at 20° C., 0.55 g/cm³ at 20°C., 0.60 g/cm³ at 20° C., 0.65 g/cm³ at 20° C., 0.70 g/cm³ at 20° C.,0.75 g/cm³ at 20° C., 0.80 g/cm³ at 20° C., 0.85 g/cm³ at 20° C., 0.90g/cm³ at 20° C., 0.95 g/cm³ at 20° C., 1.00 g/cm³ at 20° C., 1.05 g/cm³at 20° C., 1.10 g/cm³ at 20° C., 1.15 g/cm³ at 20° C., 1.20 g/cm³ at 20°C., 1.25 g/cm³ at 20° C., 1.30 g/cm³ at 20° C., 1.35 g/cm³ at 20° C.,1.40 g/cm³ at 20° C., 1.45 g/cm³ at 20° C., and 1.50 g/cm³ at 20° C. Insome embodiments, the fluid or liquid density can be any density so longas the device is configured to produce a high amplitude, low frequencybroadband oscillating pressure wave having more than 50% of its averagepower spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a modeltest lung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

FIG. 29 illustrates a patient ventilation system 900 (also referred toherein as a “Hansen Ventilator”) utilizing two bubblers 985 and 980(also referred to as a “bubbleators” or “High Amplitude Bubblers” (HAB)or “positive end-expiratory pressure control conduits” or “peakinspiratory pressure control conduits” or in some embodiments, “simpleconduits”) submerged in a fluid 965 and configured to modulate airwaypressures in a patient receiving Bi-PAP. However, in other embodimentsthe two bubblers 985 and 980 need not be used, and may be replaced bysimple conduits (not shown). In other embodiments, more than twobubblers and/or simple conduits may be used. In yet other embodiments,the bubblers (and/or simple conduits) may each have substantiallysimilar lengths and diameters or different lengths and diameters. A gassource 910 supplies a bias flow of pressurized gas to patient conduit950 and bubbler conduit 940. The lengths and cross-sectional shapes ofthe bubblers 985 and 980 (or simple conduits), the patient conduit 950and the bubbler conduit 940 are preferably short and substantiallycircular or slightly oval in shape. However, any or all of the bubblers985 and 980 (or simple conduits) the patient conduit 950 and the bubblerconduit 940 can have any length or cross-sectional shape including butnot limited to: square, rectangular, triangular etc., without departingfrom the spirit of the present disclosure.

In some embodiments the length of each of the bubblers 985 and 980 asmeasured from the distal edge of the bubbler exit portion to the outsideof the bubbler elbow or any point inside of the bubbler elbow can beabout 0.5 cm to 100 cm, desirably 1 cm to 50 cm, preferably 3 cm to 15cm. That is, in some embodiments, the length of each of the bubblers 985and 980 as measured from the distal edge of the bubbler exit portion tothe outside of the bubbler elbow or any point inside of the bubblerelbow can be at least, equal to, greater than or any number in betweenabout 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 21cm, 22 cm, 23 cm, 24 cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30 cm, 31cm, 32 cm, 33 cm, 34 cm, 35 cm, 36 cm, 37 cm, 38 cm, 39 cm, 40 cm, 41cm, 42 cm, 43 cm, 44 cm, 45 cm, 46 cm, 47 cm, 48 cm, 49 cm and 50 cm.Although not a desirable embodiment, the length of the bubblers 985 and980 as measured from the distal edge of the bubbler exit portion to theoutside of the bubbler elbow or any point inside of the bubbler elbowcan be at least, equal to, greater than or any number in between about50 cm, 55 cm, 60 cm, 65 cm, 70 cm, 75 cm, 80 cm, 85 cm, 90 cm, 95 cm,and 100 cm. In some embodiments, the length of the bubblers as measuredfrom the distal edge of the bubbler exit portion to the outside of thebubbler elbow or any point inside of the bubbler elbow can be any lengthso long as the device is configured to produce a high amplitude, lowfrequency broadband oscillating pressure wave having more than 50% ofits average power spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2 L/minin a model test lung system comprising a hermetically sealed silasticlung within a calibrated plethysmograph.

In certain embodiments of the bubblers 985 and 980 (and/or simpleconduits), the diameters of the bubblers 985 and 980 (and/or simpleconduits) are about 0.1 cm to 10 cm, desirably 0.25 cm to 5 cm,preferably 1 cm to 2 cm. That is, in some embodiments, the diameter ofthe bubblers 985 and 980 (and/or simple conduits) can be at least, equalto, greater than or any number in between about 0.25 cm, 0.5 cm, 0.75cm, 1.0 cm, 1.25 cm, 1.5 cm, 1.75 cm, 2.0 cm, 2.25 cm, 2.5 cm, 2.75 cm,3.0 cm, 3.25 cm, 3.5 cm, 3.75 cm, 4.0 cm, 4.25 cm, 4.5 cm, 4.75 cm and5.0 cm. Although not a desirable embodiment, the diameter of thebubblers 985 and 980 (and/or simple conduits) can be at least, equal to,greater than or any number in between about 5 cm, 5.5 cm, 6.0 cm, 6.5cm, 7.0 cm, 7.5 cm, 8.0 cm, 8.5 cm, 9.0 cm, 9.5 cm, and 10.0 cm. In someembodiments, the diameter of the bubblers 985 and 980 (and/or simpleconduits) can be any size so long as the device is configured to producea high amplitude, low frequency broadband oscillating pressure wavehaving more than 50% of its average power spectra occur below about 10Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the bias gasflow is at least 2 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph.

In some embodiments, the cross-sectional area of at least one of thebubblers (or simple conduits), as defined by a plane transverse to thelongitudinal axis of the bubbler, is about 0.005 cm² to 350 cm²,desirably 0.2 cm² to 80 cm², and preferably about 3.10 cm² to 13 cm².That is, in some embodiments, the cross-sectional area of the bubblerscan be at least, equal to, greater than, or any number in between about0.2 cm², 0.5 cm², 0.75 cm², 1 cm², 2 cm², 3 cm², 4 cm², 5 cm², 6 cm², 7cm², 8 cm², 9 cm², 10 cm², 11 cm², 12 cm², 13 cm², 14 cm², 15 cm², 16cm², 17 cm², 18 cm², 19 cm², 20 cm², 25 cm², 30 cm², 35 cm², 40 cm², 45cm², 50 cm², 55 cm², 60 cm², 65 cm², 70 cm², 75 cm², and 80 cm².Although not a desirable embodiment, the cross-sectional area of thebubblers can be at least, equal to, greater than, or any number inbetween about 80 cm², 90 cm², 100 cm², 110 cm², 120 cm², 130 cm², 140cm², 150 cm², 160 cm², 170 cm², 180 cm², 190 cm², 200 cm², 210 cm², 220cm², 230 cm², 240 cm², 250 cm², 260 cm², 270 cm², 280 cm², 290 cm², 300cm², 310 cm², 320 cm², 330 cm², 340 cm², and 350 cm². In someembodiments, the cross-sectional area of the bubblers can be any size solong as the device is configured to produce a high amplitude, lowfrequency broadband oscillating pressure wave having more than 50% ofits average power spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2 L/minin a model test lung system comprising a hermetically sealed silasticlung within a calibrated plethysmograph.

The depth at which the bubblers 980 and 985 (and/or simple conduits) aresubmerged in the fluid 965 can be measured from the fluid surface toeither the elbow of the bubbler, the bubbler exit portions, or any otherportion of the bubblers there between, or the distal end of the simpleconduit, if any. In some embodiments of the patient ventilation system900, the depth at which the bubblers 980 and 985 (and/or simpleconduits) are submerged in the fluid 965 is about 0.1 to 500 cm,desirably 1 cm to 200 cm, and preferably about 1.5 cm to 50 cm. That is,in some embodiments, the depth of the bubblers (and/or simple conduits)as measured from the fluid surface to either the bubbler elbow, thebubbler exit portion, any other portion of the bubbler or simple conduitthere between, can be at least, equal to, greater than, or any number inbetween about 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30cm, 31 cm, 32 cm, 33 cm, 34 cm, 35 cm, 36 cm, 37 cm, 38 cm, 39 cm, 40cm, 41 cm, 42 cm, 43 cm, 44 cm, 45 cm, 46 cm, 47 cm, 48 cm, 49 cm, 50cm, 51 cm, 52 cm, 53 cm, 54 cm, 55 cm, 56 cm, 57 cm, 58 cm, 59 cm, 60cm, 61 cm,62 cm, 63 cm, 64 cm, 65 cm, 66 cm, 67 cm, 68 cm, 69 cm, 70 cm,71 cm, 72 cm, 73 cm, 74 cm, 75 cm, 76 cm, 77 cm, 78 cm, 79 cm, 80 cm, 81cm, 82 cm, 83 cm, 84 cm, 85 cm, 86 cm, 87 cm, 88 cm, 89 cm, 90 cm, 91cm, 92 cm, 93 cm, 94 cm, 95 cm, 96 cm, 97 cm, 98 cm, 99 cm, 100 cm, 101cm, 102 cm, 103 cm, 104 cm, 105 cm, 106 cm, 107 cm, 108 cm, 109 cm, 110cm, 111 cm, 112 cm, 113 cm, 114 cm, 115 cm, 116 cm, 117 cm, 118 cm, 119cm, 120 cm, 121 cm, 122 cm, 123 cm, 124 cm, 125 cm, 126 cm, 127 cm, 128cm, 129 cm, 130 cm, 131 cm, 132 cm, 133 cm, 134 cm, 135 cm, 136 cm, 137cm, 138 cm, 139 cm, 140 cm, 141 cm, 142 cm, 143 cm, 144 cm, 145 cm, 146cm, 147 cm, 148 cm, 149 cm, 150 cm, 151 cm, 152 cm, 153 cm, 154 cm, 155cm, 156 cm, 157 cm, 158 cm, 159 cm, 160 cm, 161 cm, 162 cm, 163 cm, 164cm, 165 cm, 166 cm, 167 cm, 168 cm, 169 cm, 170 cm, 171 cm, 172 cm, 173cm, 174 cm, 175 cm, 176 cm, 177 cm, 178 cm, 179 cm, 180 cm, 181 cm, 182cm, 183 cm, 184 cm, 185 cm, 186 cm, 187 cm, 188 cm, 189 cm, 190 cm, 191cm, 192 cm, 193 cm, 194 cm, 195 cm, 196, 197 cm, 198 cm, 199 cm, and 200cm. Although not a desirable embodiment, the depth of the bubblers(and/or simple conduits) as measured from the fluid surface to eitherthe bubbler elbow, the bubbler exit portion, any other portion of thebubbler or simple conduit there between can be at least, equal to,greater than, or any number in between about 200 cm, 210 cm, 220 cm, 230cm, 240 cm, 250 cm, 260 cm, 270 cm, 280 cm, 290 cm, 300 cm, 310 cm, 320cm, 330 cm, 340 cm, 350 cm, 360 cm, 370 cm, 380 cm, 390 cm, 400 cm, 410cm, 420 cm, 430 cm, 440 cm, 450 cm, 460 cm, 470 cm, 480 cm, 490 cm, and500 cm. In some embodiments, the depth at which the bubblers 980 and 985(and/or simple conduits) can be submerged in the fluid 965, as measuredfrom the fluid surface to either the bubbler elbow, the bubbler exitportion, or any other portion of the bubbler there between, can be anydepth so long as the device is configured to produce a high amplitude,low frequency broadband oscillating pressure wave having more than 50%of its average power spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz,6 Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2L/min in a model test lung system comprising a hermetically sealedsilastic lung within a calibrated plethysmograph.

Gas delivered by the gas source 910 may comprise atmospheric gases orany combination, mixture, or blend of suitable gases, including but notlimited to: atmospheric air, oxygen, nitrogen, carbon dioxide, helium,or combinations thereof. The gas source 910 may comprise a gascompressor, mechanical ventilator, an electromechanical ventilator, acontainer of pressurized gas, a substantially portable container ofpre-pressurized gas, a gas-line hookup (such as found in a hospital) orany other suitable source of pressurized gas, or combinations thereof.The gas source 910 is preferably controlled or configured to have asubstantially constant bias gas flow rate which can be controlled by thecare giver and adjusted according to the individual characteristics ofeach patient. However, in some embodiments the gas source can becontrolled or configured to have a variable bias gas flow rate whichincreases or decreases over time or during breaths. The patientventilation system 900 or gas source 910 may also include one or moreflow control devices (not shown) such as a mechanical valve, anelectronically controlled mechanical valve, a rotameter, a pressureregulator, a flow transducer, or combinations thereof. Bias gas flowrates, which are commonly used in the art, typically range from about 2L/min to about 10 L/min. However, one of skill in the art willunderstand that bias gas flow rates below about 2 L/min and above about10 L/min can also be used. For example, larger patients will requirelarger bias gas flows and it can be desirable to have increasing ordecreasing bias flow rates during inhalation, exhalation, or both.

In some embodiments, the bias gas flow rate is about 0.1 L/min to 30L/min, 1 L/min to 20 L/min, preferably 2 L/min to 10 L/min. That is, insome embodiments, the bias gas flow rate can be at least, equal to,greater than or any number in between about 1 L/min, 2 L/min, 3 L/min, 4L/min, 5 L/min, 6 L/min, 7 L/min, 8 L/min, 9 L/min, 10 L/min, 11 L/min,12 L/min, 13 L/min, 14 L/min, 15 L/min, 16 L/min, 17 L/min, 18 L/min, 19L/min, and 20 L/min. Although not a desirable embodiment, the bias gasflow rate can be at least, equal to, greater than or any number inbetween about 20 L/min, 21 L/min, 22 L/min, 23 L/min, 24 L/min, 25L/min, 26 L/min, 27 L/min, 28 L/min, 29 L/min, and 30 L/min. In someembodiments, the bias gas flow rate can be any rate so long as thedevice is configured to produce a high amplitude, low frequencybroadband oscillating pressure wave having more than 50% of its averagepower spectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4Hz, 3 Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a modeltest lung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

The patient conduit 950 can include a high pressure “pop-off' or“pop-open” safety valve 920 to protect the patient (not shown) fromreceiving airway pressures greater than a pre-determined threshold tohelp prevent lung damage and to prevent high pressures from reaching thepatient in the unlikely event that the patient circuit is occludedbetween the patient and the gas exiting the system through the fluidcontainer. Additionally, the patient conduit 950 can include a lowpressure “pop-open” or one way valve (not shown) to protect the patientfrom receiving airway pressures lower than a pre-determined threshold,for example sub-atmospheric pressures. In this manner, the one way valvecan help prevent alveoli from collapsing, help prevent the patient frominhaling fluid 965, and help prevent the patient from re-breathingexhalation gases. Fresh gas of controlled concentration (not shown) canalso be supplied to the one way valve.

A Heat and Moisture Exchanger (HME) (not shown) can also be included inthe patient ventilation system 900 to control the temperature andmoisture content of gas delivered to the patient interface.

Continuing with FIG. 29, Bias gas flows from the gas source 910 to thepatient interface 930 for inhalation by the patient. The patientinterface 930 can be invasive or non-invasive, including but not limitedto: facial or nasal masks, nasal prongs, tube(s) placed in nasalpharynx, endotracheal tubes, tracheostomy tubes, or combinationsthereof. Bias gas and patient exhalation gases flow through bubblerconduit 940 to the bubblers which are placed in a container 960 holdinga fluid 965. The fluid 965 may comprise any number of suitable fluids orliquids exhibiting a wide range of densities, masses and viscositiesincluding, but not limited to: water, oil, ethylene glycol, ethanol,fluids containing hydrocarbons, or combinations thereof.

In some embodiments, the fluid density is about 0.5 to 1.5 g/cm³ at 20°C., desirably about 0.8 to 1.1 g/cm³ at 20° C., and preferably about0.85 to 1.05 g/cm³ at20° C. That is, in some embodiments, the fluiddensity can be at least, equal to, greater than, or any number inbetween about 0.50 g/cm³ at 20° C., 0.55 g/cm³ at 20° C., 0.60 g/cm³ at20° C., 0.65 g/cm³ at 20 ° C., 0.70 g/cm³ at 20° C., 0.75 g/cm³ at 20°C., 0.80 g/cm³ at 20° C., 0.85 g/cm³ at 20° C., 0.90 g/cm³ at 20° C.,0.95 g/cm³ at 20° C., 1.00 g/cm³ at 20° C., 1.05 g/cm³ at 20° C., 1.10g/cm³ at 20° C., 1.15 g/cm³ at 20° C., 1.20 g/cm³ at 20° C., 1.25 g/cm³at 20° C., 1.30 g/cm³ at 20° C., 1.35 g/cm³ at 20° C., 1.40 g/cm³ at 20°C., 1.45 g/cm³ at 20° C., and 1.50 g/cm³ at 20° C. In some embodiments,the fluid or liquid density can be any density so long as the device isconfigured to produce a high amplitude, low frequency broadbandoscillating pressure wave having more than 50% of its average powerspectra occur below about 10 Hz, 9 Hz, 8 Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3Hz, or 2 Hz when the bias gas flow is at least 2 L/min in a model testlung system comprising a hermetically sealed silastic lung within acalibrated plethysmograph.

The bubbler conduit 940 comprises a valve 925 placed between the twobubblers 980 and 985 (which are at different depths in the fluid 965) tocontrol mean airway pressures, the rate of ventilation, and theinspiratory time for the ventilation system 900. The valve 925 maycomprise a mechanical or electromechanical valve, or the valve may beoperated by simply pinching flexible tubing (by hand or otherwise). Thevalve 925 may be electronically controlled or mechanically controlledsuch that the user is able to set the ventilation rate and inspiratorytime or the ratio of inspiratory to expiratory time. The valve 925 ispreferably “normally open” such that in the event of failure the valvewould be open and the patient would be subjected to the lower pressureand capable of breathing freely through the system. When the valve 925is open, bias gases flow through bubbler 985, which is set to a lesserdepth than bubbler 980, thereby controlling the mean expiratory airwaypressure (or positive end expiratory pressure) in the circuit. When thevalve 925 is closed, gas in the pressurized circuit flows throughbubbler 980, which is deeper than bubbler 985, thereby raising the meanairway pressure in the circuit (or peak inspiratory pressure) anddelivering a “mandatory breath” to the patient. The valve 925 can thenbe opened again to allow the patient to exhale, and the process may berepeated. In this manner, a patient can receive Bi-PAP ventilation (peakinspiratory pressure and positive end expiratory pressure) withsuperimposed oscillating airway pressures during both inhalation andexhalation cycles. In some embodiments, any number of valves and bubblerconduits can be used to alternate between any number of different meanairway pressures.

The angle of bubblers 980 and 985 may be altered between 0° and 180° tocontrol the amplitude and frequency of airway pressure oscillationssuperimposed on top of the airway pressure wave form for both theinhalation and exhalation cycles. In some embodiments, more than twobubblers (or simple conduits) may be used. In other embodiments, theangles of the two or more bubblers may be substantially similar. Instill other embodiments, the angles of the two or more bubblers may bedifferent.

In some embodiments, the angle of one or more of the bubblers asmeasured with respect to a line normal to the surface of the fluid orwith respect to a vertical axis is about 1° to 89° or about 91° to 180°,preferably about 100° to 170°. That is, in some embodiments, the angleof one or more of the bubblers as measured with respect to a line normalto the surface of the fluid or with respect to a vertical axis can be atleast, equal to, greater than or any number in between about 1°, 2°, 3°,4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°,190, 20°, 21°, 22°, 230, 24°, 25°, 26°, 270, 28°, 290, 30°, 31°, 32°,330, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45°, 46°,470, 48°, 490, 50°, 51°, 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59°, 60°,61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70°, 71°, 72°, 73°, 74°,75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84°, 85°, 86°, 87°, 88°,89°, 91°, 92°, 93°, 94°, 95°, 96°, 97°, 98°, 99°, 100°, 101°, 102°,103°, 104°, 105°, 106°, 107°, 108°, 109°, 110°, 111°, 112°, 113°, 114°,115°, 116°, 117°, 118°, 119°, 120°, 121°, 122°, 123°, 124°, 125°, 126°,127°, 128°, 129°, 130°, 131°, 132°, 133°, 134°, 135°, 136°, 137°, 138°,139°, 140°, 141°, 142°, 143°, 144°, 145°, 146°, 147°, 148°, 149°, 150°,151°, 152°, 153°, 154°, 155°, 156°, 157°, 158°, 159°, 160°, 161°, 162°,163°, 164°, 165°, 166°, 167°, 168°, 169°, 170°, 171°, 172°, 173°, 174°,175°, 176°, 177°, 178°, 179°, and 180°. In some embodiments, the angleof the bubblers as measured with respect to a line normal to the surfaceof the fluid or with respect to a vertical axis can be any angle that isnot 0° or 90° so long as the device is configured to produce a highamplitude, low frequency broadband oscillating pressure wave having morethan 50% of its average power spectra occur below about 10 Hz, 9 Hz, 8Hz, 7 Hz, 6 Hz, 5 Hz, 4 Hz, 3 Hz, or 2 Hz when the bias gas flow is atleast 2 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.

Referring back to FIG. 1, the action of bubbles 190 escaping from thebubbler exit portion 180 serves to modulate the pressure of the gases inthe patient ventilation system 100 which in turn modulates the pressureof the gases delivered to the patient's airway (not shown), which isconnected to the patient interface 130. In general, gravity is asignificant force by which gas pressures are modulated in the patientventilation system 100. Gas flowing through the bubbler 170 mustovercome the weight of the fluid column above the bubbler exit portion180 to allow bubbles to escape, generating back pressure. As bubblesescape, they form a less dense, low pressure region above the bubblerexit portion, thereby reducing or even reversing the back pressure.Liquid (or fluid) can then rush back into the bubbler (gurgling) togenerate greater back pressure and the cycle can repeat itself. Theinertia of the liquid rushing back into the bubbler is reversed andaccelerated back out the bubbler, generating air pressure oscillationsin the conduit. The frequencies and amplitudes of the oscillations arecontrolled by: (1) the angle of the bubbler; (2) the bias gas flow rate;(3) the depth of the bubbler in the fluid (4) the length of the bubbler;(5) the diameter or cross-sectional area of the bubbler; and (6) thedensity of the fluid. The angle of the bubbler and the bias gas flowrate are significant features, which can be modulated to vary theamplitudes and frequencies of the oscillations.

More embodiments concern methods of using one or more of theaforementioned compositions to assist the breathing of a subject (e.g.,an adult, child, infant human being or a mammal). By some approaches, asubject in need of breathing assistance is identified or selected andsaid subject is joined to one or more of the devices described herein.In some aspects the subject is attached to the device by nasal prongsand in other embodiments, the subject is attached to the device byfacial or nasal masks, tube(s) placed in the nasal pharynx, endotrachealtubes, tracheostomy tubes, or combinations thereof. Once the subject anddevice are connected, gas flow is initiated. Preferable gas flows forinfants are 1 to 10 L/min, whereas adults may require gas flows of 1 to30 L/min and large mammals may require 1 to 100 L/min or more.Optionally, the frequency, amplitude of oscillating pressure, or volumeof gas delivered is monitored so as to adjust the breathing assistancefor the particular subject. By modulating the angle of the bubbler, thebias gas flow rate, or the depth of bubbler in the fluid, one mayregulate the frequency and amplitude of the oscillations and theseaspects may be automated in some embodiments (e.g., executable by acomputer, software, and/or hardware). In some embodiments, a devicehaving a particular length of bubbler, diameter or cross-sectional areaof bubbler, or particular liquid density can be selected for a subject'sunique needs. That is, in some embodiments, a patient in need ofbreathing assistance is selected or identified and a breathingassistance device, as described herein, is selected or identifiedaccording to a subject's age, size, or therapeutic need.

Preferred embodiments include a method for providing continuous positiveairway pressure with oscillating positive end-expiratory pressure to asubject by providing any of the devices or apparatuses described herein,releasing gas from the gas source into the apparatus and delivering thegas to the subject. Other preferred embodiments include a method forincreasing the volume of gas delivered to a subject by providing any ofthe breathing assistance devices or apparatuses described herein,adjusting the angle of the distal end of the conduit with respect to avertical axis and releasing gas from the gas source into the apparatusto deliver gas to the subject. In some embodiments, the distal end ofthe conduit is adjusted to an angle greater than or equal to betweenabout 91-170 degrees, between about 95-165 degrees, between about100-160 degrees, between about 105-155 degrees, between about 110-150degrees, between about 115-145 degrees, between about 120-140 degrees,between about 125-135 degrees, between about 130-140 degrees, or about135 degrees with respect to a vertical axis. In other embodiments, thedistal end of the conduit is adjusted to an angle of about 135 degreeswith respect to a vertical axis. In yet other embodiments, the distalend of the conduit is adjusted to any angle, except 0 and 90 degrees,wherein the breathing assistance apparatus is configured to produce anoscillating pressure wave having more than 50% of its average powerspectra occur below about 7 Hz when the bias flow of gas is at least 2L/min in a model test lung system comprising a hermetically sealedsilastic lung within a calibrated plethysmograph.

The patient ventilation systems described herein were evaluated inseveral bench tests and animal experiments. In one set of experiments, amodel system was used to evaluate the performance of the embodimentsdescribed herein (Example 1). The silastic model lung test is a wellaccepted system to evaluate the performance of a breathing apparatus.

In another set of experiments, the patient ventilation system of FIG. 1was evaluated in bench tests to determine the affect of the angle of thebubbler on the frequency bandwidth and amplitude composition of thepressure oscillations. It was discovered that the angle of the bubblergreatly affected both the frequency bandwidth and amplitude compositionof the pressure oscillations (see Example 2).

In other experiments, the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the angle of thebubbler on the frequencies and amplitudes of the pressure oscillations,as well as, the corresponding volume of gas delivered to the silasticlung model. It was discovered that the bubbler angle has an unexpectedand profound influence on the amplitude of oscillations in airwaypressure and volume delivered to the mechanical lung model (see Example3).

In yet another experiment, the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the bias gas flowrate on the amplitude of oscillations in airway pressure and lung volumedelivered to the lung model. It was discovered that in general, as thebias flow rate increases, the amplitude of oscillations in airwaypressure and lung volume delivered to the lung model also increase.Furthermore, surprising and unexpected results were obtained showingthat the Funnel configuration used in Nekvasil, which yields the highestamplitudes in pressure oscillations, does not yield the highestamplitudes of gas delivered to the lung model (see Example 4).

In another set of experiments, the patient ventilation system of FIG. 1was evaluated in bench tests to determine the affect of the depth of thebubbler in the fluid on the mean airway pressure and on the amplitude ofairway pressure oscillations, given a constant angle, bubbler diameter,bubbler length and bias gas flow rate. It was discovered that, ingeneral, the deeper the bubbler is in the fluid, the greater the meanairway pressure that is generated. It was also discovered that, for thisembodiment, a depth between about 7 and 9 cm yielded the maximumamplitude of airway pressure oscillations (see Example 5).

In another set of experiments, the patient ventilation system of FIG. 1was evaluated in bench tests to determine the affect of the length anddiameter on the amplitude of airway pressure oscillations. It wasdiscovered that, for this embodiment, a bubbler diameter of 1.5 cm and abubbler length of 9 cm yielded the highest amplitudes of airway pressureoscillations (see Example 6).

In other experiments, the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the angle of thebubbler on the amplitude and frequency characteristics of the powerspectra derived from the airway pressure time signal. It was discoveredthat the angle of the bubbler had a great impact on the amplitude andfrequency characteristics of the power spectra, especially for anglesgreater than 90° (see Example 7).

In another set of experiments, the patient ventilation system of FIG. 1was evaluated in bench tests to determine the affect of the bias gasflow rate on the amplitude and frequency characteristics of the powerspectra derived from the airway pressure time signal. It was discoveredthat the bias gas flow rate had a great impact on the amplitude andfrequency characteristics of the power spectra (see Example 8).

In another set of experiments, the funnel as described in the Nekvasilreference (cited in the background section above) and the patientventilation system of FIG. 1 were evaluated in bench tests to determinethe amplitudes of the airway pressure oscillations and the delivered gasvolume oscillations of each device. It was discovered that the Nekvasilfunnel produced high amplitude pressure oscillations in a narrowfrequency bands centered around 9 Hz and harmonics of 9 Hz, relativelyindependent of bias gas flow rates. It was also discovered that theNekvasil funnel produced amplitude pressure oscillations with short timedurations, leading to small volumes of gas being delivered to the modellung. In contrast, it was shown that patient ventilation system of FIG.1 produced high amplitude, long time duration pressure oscillations in abroad band of frequencies resulting in large volumes of gas beingdelivered to the model lung (see Example 9).

In another set of experiments, the patient ventilation system of FIG. 1was evaluated in live animal tests to determine the affect of the angleof the bubbler on oxygenation in the animals, as well as, to compare theeffectiveness of the patient ventilation system of FIG. 1 toconventional mechanical ventilation. It was discovered that the angle ofthe bubbler had a profound effect on the oxygenation of the animals. Itwas also discovered that the patient ventilation system of FIG. 1 wasmore effective at oxygenating and ventilating the animals than theconventional mechanical ventilator (see Example 10).

In another set of experiments, the patient ventilation system of FIG. 1was evaluated in live animal tests to determine the effectiveness of theventilation system in comparison to conventional mechanical ventilationwith respect to work of breathing, oxygenation and ventilationcharacteristics. It was discovered that the patient ventilation systemof FIG. 1 had a positive and profound effect on the work of breathing,oxygenation and ventilation in the animals (see Example 11).

In other experiments, the patient ventilation system of FIG. 29 wasevaluated in bench tests to compare the ventilation characteristics ofthe ventilation system with a common mechanical ventilator. It wasdiscovered that the ventilation system of FIG. 29 produced a similarairway pressure profile as the mechanical ventilator, with the exceptionof superimposed oscillations in the airway pressure during both theinspiratory and expiratory cycles (see Example 12).

In another experiment, the patient ventilation system of FIG. 29 wasevaluated in live animal tests to determine the effectiveness of theventilation system in comparison to conventional mechanical ventilationwith respect to oxygenation and ventilation. It was discovered that thepatient ventilation system of FIG. 29 had a positive and profound effecton oxygenation and ventilation in the animals (see Example 13).

EXAMPLE 1

This example describes the silastic test lung system, methods andexperiments that were performed to calculate the embodiments describedherein in this model system. FIG. 2A shows the model test lung(hermetically sealed within a calibrated plethysmograph) that was usedto bench test the patient ventilation system 100 of FIG. 1. Steel wool(not shown) can also be used to surround the silastic lung within theplethysmograph to maintain near isothermal conditions. Theplethysmograph pictured in FIG. 2A was purchased from Ingmar Medical®.The silastic test lung was made by Maquet Critical Care (Test Lung 19163 01 720 E380E). Unless stated otherwise, the lung compliance is set toabout 0.47 mL/cmH₂O and the airway resistance is set to about 200cmH₂O/L/Sec. In some embodiments, an infant head model (with an internalvolume of about 300 mL, including connectors) with Hudson nasal prongs(not shown) was connected to the silastic lung model and leak ratesaround the nasal prongs were measured at about 1.2 and 2.0 L/min atpressures of 5 and 10 cmH₂O respectively. Pressures at the airway(proximal to the nasal prongs) and inside the plethysmograph weremeasured using Honeywell® XRA515GN temperature compensated pressuresensors. Signals from the pressure sensors were recorded on a desktopcomputer via a DataTranslation DT9804-EC-I-BNC analog/digital converter.The sample frequency was 1024 Hz and the sample period was 8 seconds.The first 100 msec of data were left unfiltered in order to obviate theinitial deviations caused by the filtering.

The plethysmograph was calibrated by adding known volumes of 5, 10, 15and 20 mL to the lung model using a glass syringe and recording thepressure inside the plethysmograph. The volumes were plotted as afunction of pressure and a linear regression through the data gave acalibration factor of 1.8 mL/cmH2O. The pressure transducers werecalibrated using a two point calibration. The system was open toatmospheric pressure for a zero calibration. Pressure was then appliedto the pressure transducers and measured using a calibrated manometer(Digitron® Model PM-23). The pressures were recorded digitally using theA/D converter and averaged over two seconds of readings while sampled at1000 Hz resulting in zero and slope calibration factors.

The amplitudes of oscillations in airway pressure were calculated fromthe airway pressure signal. The pressure signals were filtered using alow-pass 4^(th) order Butterworth filter with a cut-off frequency of 50Hz prior to the amplitude analyses. A minimum threshold change in volumewas established by calculating 15% of the absolute maximum and minimumof the 8 second period of airway pressures and local maxima and minimaon the signal were found by stepping through the data. For example, inFIG. 2B a local maxima is found at point 1. Stepping forward in timethrough the data one passes the plus sign indicating the 15% threshold.Stepping further, point 2 is found. Stepping even further toward point3, the threshold plus sign is passed indicating that point 2 is aminimum. Thus, point 1 is the peak and point 2 is the trough of anoscillation. Notice the small oscillation between points 5 and 6 that isnot counted because the 15% threshold criterion was not met. The meanand standard error of the pressure oscillations were calculated for theperiod of 8 seconds of measurements. A similar process was used todetermine the amplitude of oscillations in lung volume.

EXAMPLE 2

This example describes how the patient ventilation system of FIG. 1 wasevaluated with a method (disclosed below) to determine the affect of theangle of the bubbler on the frequency bandwidth and composition of thepressure oscillations. To determine the bandwidth of the oscillation inairway pressure, the airway pressure-time waveform (unfiltered) wastransformed into the frequency domain using fast Fourier transformation(FFT). The frequencies were then filtered using a 10-point boxcar. Arelevant range of frequencies was defined as the longest set ofcontiguous frequencies with amplitudes greater than −7 dB relative tothe peak magnitude. The magnitude of oscillations is the square root ofthe sum of the real and imaginary parts of the FFT each squared, withunits of cmH₂O. Outlier frequencies that were more than 1 Hz away fromthe set of frequencies were not considered. The frequencies yielding themaximum power were also recorded. For example, FIGS. 3 and 4 showmeasurements made with the bubbler angle set to 135° and 0°respectively. At 135° the frequencies ranged from 2 to 7 Hz while at 0°the range was from 8 to 37 Hz. Note that the magnitude at 135° is muchgreater (around 4000) than at 0° (around 700) which is consistent withthe greater amplitude of airway pressure oscillations measured at 135°.

EXAMPLE 3

This example describes how the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the angle of thebubbler on the frequencies and amplitudes of the pressure oscillations,as well as the corresponding volume of gas delivered to the silasticlung model. Referring to FIG. 5, three different bubbler angleconfigurations of 0°, 90° and 135° were used to illustrate the effect ofthe bubbler angle on pressure oscillations delivered to the silasticlung model (a constant bias flow of 6 L/min was used). When the bubblerangle is oriented vertically in the liquid (0° from the vertical to thewater surface), only relatively high frequency, low-amplitude pressureoscillations are generated, resulting in very little gas being deliveredto the lung. In this configuration, the system is similar toconventional B-CPAP. When the bubbler angle is adjusted horizontally(90° from the vertical and parallel with the liquid surface) both highand low frequency oscillations in pressure are obtained with the largestamplitudes in pressure oscillations occurring at about 1.1 Hz. When thebubbler angle is adjusted to 135°, the amplitude of the airway pressureoscillations increases dramatically, while maintaining a relatively lowfrequency profile. In this position, gas flowing through the tubingreleases bubbles and periodically accelerates liquid up the tubing(gurgling) generating relatively large pressure oscillations atrelatively low frequencies (2.1-7.25 Hz). For purposes of thisapplication, low frequencies are generally defined as any frequencybelow about 10 Hz, desirably any frequency below about 7 Hz andpreferably any frequency below about 5 Hz. This configuration (135°)delivers a much greater volume of gas to the lung than either of theother two angles. Thus, the bubbler angle has an unexpected and profoundinfluence on the amplitude of oscillations in airway pressure and volumedelivered to the mechanical lung model. FIG. 5 shows a 462% increase inoscillations in volume delivered to the mechanical lung model when thebubbler 170 angle was increased from 0° to 135°. The amplitude ofoscillations in airway pressure also increased 308% when the bubbler 170angle was increased from 0° to 135°.

FIGS. 6 and 7 illustrate how the amplitude of oscillations in airwaypressure and lung volume can change for various bubbler angles between0° and 180°, given a constant bias flow rate. FIG. 8 shows how theamplitude of oscillations in airway pressure and lung volume vary forbubbler angles between 0° and 180° for a patient ventilation systemhaving another constant bias flow rate.

EXAMPLE 4

This example describes how the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the bias gas flowrate on the amplitude of oscillations in airway pressure and lung volumedelivered to the lung model. FIG. 9 demonstrates the typical effects ofbias flow on the amplitude of oscillations in airway pressure forbubbler angles of 0°, 90° and 135°, as well as, for a funnel-shapedbubbler exit portion oriented at 90°. In general, the greater the biasflow, the greater the amplitude of oscillations in airway pressures.Upon first inspection of FIG. 9, it appears that the funnel shapedbubbler exit portion oriented at 90° should deliver the most volume tothe lung given the fact that this configuration yields the largestamplitudes in pressure oscillations at the airway. However, surprisingand unexpected results were observed when measuring the amplitude ofoscillations in lung volume. FIG. 10 shows the amplitude of oscillationsin lung volume corresponding to the amplitudes of airway pressures inFIG. 9. Note that, while the funnel has by far the largest amplitudes ofairway pressures in FIG. 9, the bubbler oriented at 135° has thegreatest amplitudes of oscillations in lung volume. In order tounderstand this unexpected result, a more in-depth analysis of all ofthe variables affecting the system was made.

Referring back to FIG. 5, it was discovered that the relationshipsbetween amplitude, frequency and time duration of pressure waves controlthe amount of gas delivered to the lung. Specifically, large amplitude,low frequency, and relatively long time duration pressure oscillationsdeliver the most volume of gas to the lung. The time duration of apressure oscillation is defined by the amount of time it takes for theoscillation to complete one cycle (minima→maxima→minima). For example,in FIG. 5 with the bubbler adjusted to 90°, there is a relatively largeamplitude oscillation wave having a frequency of about 1.1 Hz. However,note the small time duration of the 1.1 Hz oscillation compared to thelarger time duration of the pressure wave when the bubbler angle is setto 135°. An oscillating pressure wave with longer time duration has moretime to deliver gas to the lung, and therefore results in more gasdelivered to the lung.

EXAMPLE 5

This example describes how the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the depth of thebubbler in the fluid on the mean airway pressure and on the amplitude ofairway pressure oscillations, given a constant angle, bubbler diameter,bubbler length and bias gas flow rate. Continuing with reference toFIGS. 1 and 5, the depth of the bubbler exit portion in the liquidcontrols the lower or mean airway pressure delivered to the lung. Thiscreates a baseline offset in pressure and lung volume to which thepressure oscillations are essentially added to or superimposed upon.Accordingly, the mean airway pressure delivered to the patient can becontrolled by adjusting the depth at which the bubbler 170 is placedbeneath the fluid surface 166. In general, the deeper the bubbler isplaced beneath the fluid surface 166, the greater the mean airwaypressure delivered to the patient. In one embodiment, the depth of thebubbler 170 in the fluid is controlled by adjusting the length and/ororientation of the bubbler conduit 140 to adjust the depth at which thebubbler 170 is placed beneath the fluid surface 166. In anotherembodiment, the depth of the bubbler 170 in the fluid is controlled bymoving the container 160 relative to the bubbler 170 to adjust the depthat which the bubbler 170 is placed beneath the fluid surface 166. In yetanother embodiment, the depth of the bubbler 170 in the fluid iscontrolled by adjusting the fluid surface 166 relative to the bubbler170, by adding or removing fluid from the container 160.

The depth of the bubbler in the fluid also affects the amplitudes of theoscillation in airway pressure. FIG. 11 illustrates one embodiment withthe bubbler 170 set to 135°, at a bias gas flow rate of 6 L/min. Thedepth of the bubbler beneath the water surface was varied between 5 and11 cm. The amplitude of oscillations in airway pressure, correspondingto depths of 5, 7, 9, and 11 cm, yielded airway pressures of 8.9±1.3,10.2±1.2, 10.3±1.3, and 9.8±1.1 cmH2O, respectively (mean±SD, n=32).

EXAMPLE 6

This example describes how the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the length anddiameter on the amplitude of airway pressure oscillations. The geometricshape of the bubbler and bias flow rate influence the rate at whichbubbles break up as they travel through and exit the bubbler. In thetypical case of using round tubing for the bubbler, the diameter andlength of the bubbler are the major bubbler geometric factors thatinfluence the amplitude of oscillations in airway pressure. FIG. 12shows how the amplitude of airway pressures change as the insidediameter of the bubbler is varied from 1.2 cm to 2.2 cm and the lengthof the bubbler is varied between 7 and 9 cm (the bias flow was heldconstant at 6 L/min). In this embodiment, the optimal geometricdimensions for the bubbler are 1.5 cm diameter and 9 cm length.

EXAMPLE 7

This example describes how the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the angle of thebubbler on the amplitude and frequency characteristics of the powerspectra derived from the airway pressure time signal. The frequencyspectrum and range of oscillations is also greatly affected by the angleof the bubbler, as can be seen in FIG. 13. The angle of the bubbler wasvaried between 0° and 180° and the airway pressure time signal wasmeasured at each of the angles shown in FIG. 13. Fourier analyses wereperformed on each of these airway pressure signals to find the powerspectra characteristics for each airway pressure signal, as can be seenin FIG. 10, demonstrating an increase in frequency range and power whenthe bubbler angle is increased from 0° to 180°, with the maximum poweramplitude occurring at about 135°. Furthermore, note the broad range offrequencies for the power spectral signals at angles greater than 90°.This broadband range of frequencies helps recruit and stabilizeatelectatic (closed) alveoli in a patient.

EXAMPLE 8

This example describes how the patient ventilation system of FIG. 1 wasevaluated in bench tests to determine the affect of the bias gas flowrate on the amplitude and frequency characteristics of the power spectraderived from the airway pressure time signal. Bias flow alters thefrequency range of the oscillations, with higher bias flows shifting thefrequency spectrum toward higher frequencies and lower bias flowsshifting the frequency spectrum toward lower frequencies. FIG. 14 showshow the power spectra vary in the frequency domain with different biasflow rates (the bubbler angle was held constant at 135°). The majorrange of oscillations increases from a range of about 2 to 5 Hz (biasflow of 2 L/min) to a range of 1 to 9 Hz (bias flow of 12 L/min). Thus,in general, higher bias flows lead to an increase in the magnitude andrange of frequencies of oscillations.

EXAMPLE 9

This example describes how the funnel, as described in the Nekvasilreference (cited in the background section above), and the patientventilation system of FIG. 1 were evaluated in bench tests to determinethe amplitudes of the airway pressure oscillations and the delivered gasvolume oscillations of each device. In this experiment, a 30 mm funnel,identical to the one used in the Nekvasil reference, was affixed to theend of the bubbler. Measurements of airway pressures were obtained andanalyzed in the frequency domain using FFT to determine the frequencycomposition of oscillations in Paw caused by bubbles exiting the funnel.FIG. 15 shows the normalized amplitude of the power spectra of airwaypressure oscillations vs. frequency for 6, 8, and 10 L/min bias flowrates. FIG. 15 reveals that changes in bias flow affected the amplitudesof oscillations, while the frequencies of oscillation remainedrelatively constant and independent of bias flow. Note how consistentthe airway pressure rises in time and the narrowness (short timeduration) of the pressure spikes. Also, notice that the pressure waveform resembles a half sine wave. This is readily seen in the powerspectral analysis where the major frequency of oscillation is around 9Hz and the subsequent spikes are just harmonics of the 9 Hz, namely, 18,27, 36, etc. Also, note that the amplitude in oscillations increases asbias flow increases, however, the frequency remains constant.

FIG. 16 shows how the volume of gas delivered to the lung model variedfor each of the bias flow rates of FIG. 15. FIG. 16 shows that, eventhough the amplitude in airway pressure oscillations increased as biasflow increased, the volume of gas delivered to the lung model did notincrease. This is due to the short time duration of the airway pressurespikes, which did not last long enough to push very much gas into thelung. This phenomenon is more evident in FIG. 17, which compares theairway pressure using the funnel (gray signal) with the airway pressureof the bubbler (black signal) adjusted to an angle of 135° without afunnel. Both measurements were taken with bias flow rates of 8 L/min.Note that the bubbler delivers pressures with a greater time durationresulting in larger volumes of gas delivered to the patient. Theoscillations in pressure delivered by the funnel are shorter in durationthan the bubbler and the funnel delivers only about 60% of the tidalvolume delivered by the bubbler.

FIG. 18 shows the normalized amplitude of the power spectra of airwaypressure oscillations vs. frequency for the bubbler adjusted to an angleof 135°, without a funnel and with an 8 L/min bias flow rate. Note thebroad-band nature of the power spectra in FIG. 18 compared to the narrowband power spectra in FIG. 15. This is considered to be good forrecruiting and maintaining collapsed alveoli, as previously discussed.

FIG. 19 shows the delivered gas volume in time for the bubbler at 135°at 8 L/min discussed above. Dashed Lines represent maximum and minimumvolumes representing an average volume delivered to the lung of 4.0 mL,which is larger than the volume delivered by the funnel (FIG. 16). Also,note that the signal of FIG. 19 has larger variations in size andfrequency of oscillations in volume compared to the funnel.

EXAMPLE 10

This example describes how the patient ventilation system of FIG. 1 wasevaluated in live animal tests to determine the affect of the angle ofthe bubbler on oxygenation in the animals as well as to compare theeffectiveness of the patient ventilation system of FIG. 1 toconventional mechanical ventilation. In this experiment, New ZealandWhite rabbits were used to study the effects of the “Bubbleator” CPAP onoxygenation of arterial blood (PaO2) and removal of carbon dioxide(PaCO2) from arterial blood. Thirteen rabbits were sedated,anesthetized, paralyzed and a tube was placed in their trachea(intubation). The animals were stabilized and managed by ventilatingthem on a conventional mechanical ventilator (CV). The animals wereparalyzed to prevent them from breathing spontaneously so measurementsof the effects of the Bubblelator on gas exchange in the lungs could beobtained independent of breathing. Measurements were made while theanimals were managed on CV and the Bubblelator with bubbler angles of0°, 90° and 135°.

Referring to FIG. 20, all of the animals failed within 60 seconds afterbeing placed on the Bubblelator angled at 0°. The criteria for failureoccurs when the arterial blood oxygen saturation of the animal dropsbelow 80%. Setting the Bubblelator to 0° is equivalent to usingconventional bubble CPAP, which is a mainstay of therapy in preterminfants. Thus, without spontaneous breathing efforts, standard B-CPAPwill not support life in these animals. When the bubbler angle wasadjusted to 90° only 4 of the 13 paralyzed rabbits were well oxygenatedand ventilated. In 9 of 13 animals the arterial blood oxygen saturationdropped below 80% within 5 minutes and thus reached the failurecriteria. However, all of the animals had good gas exchange when placedon the Bubblelator at 135°.

Referring now to FIG. 21, the mean airway pressures of the rabbits(while managed on the Bubblelator at 135°) were adjusted to the samelevel as measured when the rabbits were on CV. Surprisingly, gasexchange (PaO2) was significantly better when the rabbits were managedon the Bubblelator at 135° than while being ventilated with theexpensive mechanical CV.

EXAMPLE 11

This example describes how the patient ventilation system of FIG. 1 wasevaluated in live animal tests to determine the effectiveness of theventilation system in comparison to conventional mechanical ventilationwith respect to work of breathing, oxygenation and ventilationcharacteristics. In an experiment, twelve New Zealand White rabbits wereused to study the effects of the “Bubbleator” CPAP on “work ofbreathing” (WOB) as well as oxygenation of arterial blood (PaO2) andremoval of carbon dioxide (PaCO2) from arterial blood. The WOB wasestimated using the pressure-rate-product (PRP) method. All twelveanimals were allowed to breathe spontaneously through nasal prongsplaced into the nasal pharynx (similar to manage preterm infants onbubble CPAP). The lungs of the animals were then lavaged using 25 mL/kg0.9% saline to induce lung injury then they were managed on the twomodes of assisted ventilation, conventional bubble CPAP (B-CPAP) set to0° and High Amplitude Bubble CPAP (HAB-CPAP) set to 135. Gasconcentrations and WOB were measured under both conditions, the resultsof which can be seen in FIG. 22. While breathing on the Bubblelator at135°, two of the animals ceased spontaneous efforts altogether and athird animal had a greatly reduced WOB. The PaCO2 values of the twoapneic animals were 41 and 49 mm Hg suggesting that they were nothyperventilated (35 to 45 mm Hg is considered normal). WOB decreasedfrom 289.2±26.9 (mean±SE) on the Bubblelator at 0° to 141.0±13.1 on theBubblelator at 135° (p=0.001). The units for PRP are cmH₂O times breathsper min. P_(a)O₂ values were higher (p=0.007) with the Bubblelator setto 135° (range 49-166 mm Hg) than with the Bubblelator set to 0° (range51-135 mm Hg). P_(a)CO₂ values were not significantly different betweenthe Bubblelator set at 135° and the Bubblelator set at 0° (p=0.073)(70.9±7.2 vs. 63.9±4.9 ton). Thus, oxygenation improved during HAP-CPAP,with comparable ventilation, and reduced WOB. These results indicatethat HAB-CPAP may be useful in avoiding intubation and mechanicalventilation of patients in moderate respiratory distress.

EXAMPLE 12

This example describes how the patient ventilation system of FIG. 29 wasevaluated in bench tests to compare the ventilation characteristics ofthe ventilation system with a common mechanical ventilator. In anexperiment, eleven New Zealand White rabbits were used to compare thegas exchange characteristics of the Hansen Ventilator and a conventionalmechanical ventilator (CV). The rabbits were sedated, anesthetized andparalyzed so all of the ventilation for gas exchange was supplied by theventilators, without any spontaneous breathing. The lungs of the animalswere lavaged repeatedly with 25 mL/kg of pre-warmed 0.9% saline toproduce severe surfactant deficiency. The animals were stabilized withCV and then managed onto the Hansen Ventilator with the same settings asthe CV. Arterial blood gas and mean airway pressure measurements werethen obtained after ten minutes and paired t-tests were then used tocompare values.

EXAMPLE 13

This example describes how the patient ventilation system of FIG. 29 wasevaluated in live animal tests to determine the effectiveness of theventilation system in comparison to conventional mechanical ventilationwith respect to oxygenation and ventilation. FIG. 31 shows the averagearterial blood gas results for the animals during ventilation with theHansen Ventilator and the mechanical ventilator (CV). Note that theHansen Ventilator (labeled TCPL in FIG. 31 for “time cycled-pressurelimited”) had improved oxygenation and ventilation, which suggests thatthe bubbling created by gas exiting the exhalation circuit plays asignificant role in ventilation, and may provide additional physiologicadvantages in recruiting diseased lung units.

It is to be understood that the detailed description and specificexamples, while indicating preferred embodiments of the presentinvention, are given by way of illustration and not limitation. Manychanges and modifications within the scope of the present invention canbe made without departing from the spirit thereof, and the inventionincludes all such modifications.

1. A breathing assistance apparatus comprising: a pressurized gassource; a container comprising a liquid; and a conduit includingproximal and distal ends, the proximal end adapted for connection to thepressurized gas source, and the distal end of the conduit configured tobe submerged in the liquid, the conduit also adapted for connection to apatient interface intermediate the proximal and distal ends of theconduit, wherein the distal end of the conduit can have any angle withrespect to a vertical axis, except 0 and 90 degrees, and wherein theconduit is configured to produce an oscillating pressure wave havingmore than 50% of its average power spectra occur below about 7 Hz whenthe bias flow of gas is at least 2 L/min in a model test lung systemcomprising a hermetically sealed silastic lung within a calibratedplethysmograph.
 2. The breathing assistance apparatus of claim 1,wherein the conduit is configured to produce an oscillating pressurewave having more than 50% of its average power spectra occur betweenabout 2-5 Hz when the bias flow of gas is 2 L/min and 1-9 Hz when thebias flow of gas is 12 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph. 3.The breathing assistance apparatus of claim 1, wherein the conduit isconfigured to produce airway pressure oscillation frequencies of betweenabout 1-10 Hz, between about 2-9 Hz, between about 2-7 Hz, or betweenabout 2-5 Hz when the bias flow is 6 L/min in a model test lung systemcomprising a hermetically sealed silastic lung within a calibratedplethysmograph.
 4. The breathing assistance apparatus of claim 1,wherein the conduit is configured to deliver an average volume of gas ofabout 4.0 ml when the bias flow of gas is 8 L/min in a model test lungsystem comprising a hermetically sealed silastic lung within acalibrated plethysmograph.
 5. A breathing assistance apparatuscomprising: a pressurized gas source; a container comprising a liquid;and a conduit including proximal and distal ends, the proximal endadapted for connection to the pressurized gas source, and the distal endof the conduit configured to be submerged in the liquid, the conduitalso adapted for connection to a patient interface intermediate theproximal and distal ends of the conduit, wherein the distal end of theconduit is angled greater than 90 degrees with respect to a verticalaxis.
 6. The breathing assistance apparatus of claim 5, wherein thedistal end of the conduit is angled greater than or equal to betweenabout 91-170 degrees, between about 95-165 degrees, between about100-160 degrees, between about 105-155 degrees, between about 110-150degrees, between about 115-145 degrees, between about 120-140 degrees,between about 125-135 degrees, between about 130-140 degrees, or about135 degrees with respect to a vertical axis.
 7. The breathing assistanceapparatus of claim 6, wherein the distal end of the conduit is angled toabout 135 degrees with respect to a vertical axis.
 8. The breathingassistance apparatus of claim 5, further comprising a conduit swivelmember at the distal end of the conduit configured to adjust the angleof the distal end of the conduit with respect to the vertical axis. 9.The breathing assistance apparatus of claim 8, wherein the conduitswivel member further comprises a plurality of marks that indicate theangle of the distal end of said conduit with respect to the verticalaxis.
 10. The breathing assistance apparatus of claim 8, wherein theconduit swivel member is automated such that a user can manually orautomatically adjust the angle of said distal end of said conduit withrespect to the vertical axis.
 11. The breathing assistance apparatus ofclaim 10, further comprising a computer configured to operate saidswivel member upon user instruction and thereby automatically adjust theangle of said distal end of said conduit with respect to the verticalaxis.
 12. The breathing assistance apparatus of claim 5, wherein thedistal end of the conduit is substantially circular having an insidediameter of between about 1-3 cm, between about 1.2-2.0 cm, betweenabout 1.3-1.8 cm, between about 1.4-1.6 cm, or about 1.5 cm.
 13. Thebreathing assistance apparatus of claim 5, wherein the angled portion ofthe distal end of the conduit has a length of between about 5-12 cm,between about 6-11 cm, between about 7-10 cm, between about 8-9.5 cm, orabout 9 cm.
 14. The breathing assistance apparatus of claim 5, whereinthe distal end of the conduit is submerged to a depth of about between3-200 cm, between about 5-11 cm, about 5 cm, about 7 cm, about 9 cm, orabout 11 cm.
 15. The breathing assistance apparatus of claim 5, whereinthe liquid has a density of between about 0.5-1.5 g/cm3 at 20° C. 16.The breathing assistance apparatus of claim 5, wherein the liquid iswater.
 17. The breathing assistance apparatus of claim 5, wherein theconduit is configured to produce an oscillating pressure wave havingmore than 50% of its average power spectra occur below about 7 Hz whenthe bias flow of gas is 2 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph.18. The breathing assistance apparatus of claim 5, wherein the conduitis configured to produce an oscillating pressure wave having more than50% of its average power spectra occur between about 2-5 Hz when thebias flow of gas is 2 L/min and 1-9 Hz when the bias flow of gas is 12L/min in a model test lung system comprising a hermetically sealedsilastic lung within a calibrated plethysmograph.
 19. The breathingassistance apparatus of claim 5, wherein the conduit is configured toproduce airway pressure oscillation frequencies of between about 1-10Hz, between about 2-9 Hz, between about 2-7 Hz, or between about 2-5 Hzwhen the bias flow is 6 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph.20. The breathing assistance apparatus of claim 5, wherein the conduitis configured to deliver an average volume of gas of about 4.0 ml whenthe bias flow of gas is 8 L/min in a model test lung system comprising ahermetically sealed silastic lung within a calibrated plethysmograph.21. The breathing assistance apparatus of claim 5, further comprising agas compressor or a mechanical or electromechanical ventilator thatprovides gas to said breathing assistance apparatus.
 22. A method forproviding continuous positive airway pressure with oscillating positiveend-expiratory pressure to a subject, comprising: providing a breathingassistance apparatus as set forth in claim 5; releasing gas from saidpressurized gas source into said conduit of said breathing assistanceapparatus; and delivering said gas to said subject.
 23. The method ofclaim 22, wherein the distal end of the conduit is adjusted to an anglegreater than or equal to between about 91-170 degrees, between about95-165 degrees, between about 100-160 degrees, between about 105-155degrees, between about 110-150 degrees, between about 115-145 degrees,between about 120-140 degrees, between about 125-135 degrees, betweenabout 130-140 degrees, or about 135 degrees with respect to a verticalaxis.
 24. The method of claim 22, wherein the distal end of the conduitis adjusted to an angle of about 135 degrees with respect to a verticalaxis.
 25. The method of claim 22, wherein the distal end of the conduitis adjusted to any angle, except 0 and 90 degrees, wherein the breathingassistance apparatus is configured to produce an oscillating pressurewave having more than 50% of its average power spectra occur below about7 Hz when the bias flow of gas is at least 2 L/min in a model test lungsystem comprising a hermetically sealed silastic lung within acalibrated plethysmograph.
 26. A method for increasing the volume of gasdelivered to a subject by a bubble continuous positive airway pressure(B-CPAP) device, comprising: providing a breathing assistance apparatusas set forth claim 8; adjusting the angle of the distal end of theconduit to greater than 90 degrees with respect to a vertical axis;releasing gas from said pressurized gas source into said conduit of saidbreathing assistance apparatus; and delivering said gas to said subject.27. The method of claim 26, wherein the distal end of the conduit isadjusted to an angle greater than or equal to between about 91-170degrees, between about 95-165 degrees, between about 100-160 degrees,between about 105-155 degrees, between about 110-150 degrees, betweenabout 115-145 degrees, between about 120-140 degrees, between about125-135 degrees, between about 130-140 degrees, or about 135 degreeswith respect to a vertical axis.
 28. The method of claim 26, wherein thedistal end of the conduit is adjusted to an angle of about 135 degreeswith respect to a vertical axis.
 29. The method of claim 26, wherein thedistal end of the conduit is adjusted to any angle, except 0 and 90degrees, wherein the breathing assistance apparatus is configured toproduce an oscillating pressure wave having more than 50% of its averagepower spectra occur below about 7 Hz when the bias flow of gas is atleast 2 L/min in a model test lung system comprising a hermeticallysealed silastic lung within a calibrated plethysmograph.